ASPECTS OF THE

GEOCHEMISTRY OF ,

NICKEL AND

Meagan E. Clissold BAppSc(Hons), UWS

This thesis is submitted for the degree of

Doctor of Philosophy

in the University of Western Sydney

July 2007 ACKNOWLEDGEMENTS

I wish to sincerely thank my supervisor Professor Peter Williams for sharing his wealth of knowledge in chemistry and mineralogy. His enthusiasm, guidance and support through out this study are greatly appreciated. I would also like to thank my co-supervisor Professor Peter Leverett, for his invaluable insight in many fields, especially crystallography. Jim Sharpe is thanked for his assistance with fieldwork and for sharing his experience in mineralogy. David Colchester is acknowledged for determining the optical properties of gillardite.

Auzex Resources Limited is thanked for permission to work on the Wolfram pipe deposit. I am grateful for the assistance and interest of company staff, particularly Dr. Roger Mustard, Kevin Chard and Ed Hammond. Northparkes Mines is thanked for permission to work on their deposits. Allan Ryan of Northparkes

Mines provided details concerning groundwater analyses. Professor Erik Melchiorre

(California State University, San Bernardino) is thanked for stable isotope data.

Valuable technical assistance was provided by Malcolm Tiddy and Wayne

Higginbotham. I would like to thank the people who have helped and encouraged me throughout this work, especially Adam McKinnon, Jacqueline, Sarah, Suzie, Sandy and Tanya. I thank my fellow students, my friends, and family for their love and support.

ii DECLARATION

The work presented in this thesis is, to the best of my knowledge and belief, original except as acknowledged in the text. I hereby declare that I have not submitted this material in any form for a degree or diploma at any university or other institution of tertiary education.

……………………………

Meagan Elizabeth Clissold

July, 2007

iii TABLE OF CONTENTS

Page

SUPPORTING PUBLICATIONS……………………...…………...viii

ABSTRACT…………………………………………………………... ix

Chapter 1: INTRODUCTION………………………………...... 1 1.1 AIMS OF THIS STUDY………………………………………………... 4 1.1.1 Northparkes study………………………………..……………. 4 1.1.2 study………………………….…….………...... 5 1.1.3 Kingsgate Bi study……………….……………..………..……. 6

Chapter 2: GEOCHEMICAL EVOLUTION OF THE OXIDISED ZONES OF THE COPPER BODIES AT NORTHPARKES, NEW SOUTH WALES, AND ITS RELEVANCE FOR GEOCHEMICAL EXPLORATION……………………………….... 8 2.1 SETTING………………………………………………………………... 8 2.2 EXPERIMENTAL……………………….…………………………….. 11 2.2.1 Instrumentation………………………………………………. 11 2.2.2 Synthesis …………………………………………………….. 12 2.2.3 Solution studies………………………………………………. 12 2.3 GEOCHEMISTRY OF DEVELOPMENT OF THE OXIDISED ZONES AT NORTHPARKES…………………………………………….. 15 2.3.1 …………………………………………... 15 2.3.2 , and …………………………….. 25 2.4 GEOCHEMICAL OF COPPER FROM THE OXIDISED ZONES AT NORTHPARKES…………………….…………. 28

iv Chapter 3: THE GEOCHEMISTRY OF FORMATION OF LAVENDULAN…………………………………………..………….. 32 3.1 BACKGROUND……………………………………….……………… 32 3.2 EXPERIMENTAL…………………………………….……………….. 34 3.2.1 Powder X-ray diffraction (XRD)………………………...... 34 3.2.2 Total reflectance X-ray fluorescence (TRXRF) spectrometry……………………………………...……... 34 3.2.3 Scanning electron microscopy (SEM)……………...………... 35 3.2.4 Electron microprobe analysis…………………….…………... 35 3.2.5 Atomic absorption spectroscopy (AAS)……....……………... 35 3.2.6 Lavendulan synthesis ………………………………………... 36 3.2.7 Solution studies……………………………..………………... 36 3.3 GEOCHEMISTRY OF FORMATION…………………… 39 3.3.1 Phase relationships…………………………………………… 39 3.4 SOLID SOLUTION PHENOMENA INVOLVING LAVENDULAN AND RELATED MINERALS………………………….. 47

Chapter 4: GILLARDITE, Cu3NiCl2(OH)6, A NEW MINERAL FROM THE 132 NORTH DEPOSIT, WIDGIEMOOLTHA, ……………………….………………….. 54 4.1 HISTORY…………………………………...…………………………. 54 4.2 OCCURRENCE………………………………….…………………….. 55 4.3 CHEMICAL COMPOSITION………………………………….……... 56 4.4 PHYSICAL AND OPTICAL PROPERTIES………………………….. 57 4.5 SINGLE-CRYSTAL X-RAY STRUCTURE………………………….. 58 4.6 X-RAY POWDER DIFFRACTION…………………………………… 62 4.7 RELATIONSHIP OF GILLARDITE TO HERBERTSMITHITE AND OTHER POLYMORPHS……………………………………..……... 62

v Chapter 5: THE BISMUTH MINERALS OF THE KINGSGATE, NEW SOUTH WALES, DEPOSITS AND THE SUPERGENE DISPERSION OF BISMUTH……………….. 66 5.1 INTRODUCTION…………………………………………...………… 66 5.2 EXPERIMENTAL METHODS.………………………..…….………... 69 5.2.1 Powder X-ray diffraction (XRD)…………...………………... 69 5.2.2 Scanning electron microscopy (SEM)…….……..…………... 69 5.2.3 Electron microprobe analysis………………………………… 70 5.3 A SURVEY OF SECONDARY Bi AND Mo MINERALS FROM AUSTRALIAN COLLECTIONS………………………………………….. 71 5.4 THE Bi-Mo DEPOSITS OF KINGSGATE…..………..……….……... 76 5.4.1 Primary mineralogy………………..…………...……………. 80 5.4.1.1 Bismuth………………………….…………………………. 82 5.4.1.2 ……………………..…………………………. 83 5.4.1.3 “Cannizzarite”………………….…………………………... 86 5.4.1.4 Cosalite………………………...…………………………... 86 5.4.1.5 Galenobismutite……………………………………..……... 86 5.4.1.6 Ikunolite…………………………………………….……… 86 5.4.1.7 Joséite………………………………………….…………… 88 5.4.1.8 Kobellite……………………………………..……………... 88 5.4.1.9 ………………………………………………... 93 5.4.1.10 Ag-rich Pb-Bi sulfides…………………….……………… 93 5.5 THE “LOST” MINES OF KINGSGATE……………...………………. 97 5.5.1. Minerals from Maurer’s Claim…………...………………... 103 5.6 A GEOCHEMICAL MODEL FOR BISMUTH IN THE SUPERGENE ENVIRONMENT……………………...…………………. 107 5.6.1. The pH regime of the supergene zone at Kingsgate……….. 107 5.6.2. A model for Bi solubility and dispersion…………………... 110 5.6.3 Exploration implications and previous exploration campaigns in the Kingsgate region…………………………...... 119

vi REFERENCES……………………………………………………... 123

APPENDIX…………………………………………………………. 144 Table A.1 COMICS output……..………………………………… 145 Table A.2 Observed and calculated structure factors for gillardite. 146 Table A.3 Crystallographic Information File (CIF) for gillardite… 151

vii SUPPORTING PUBLICATIONS

Clissold, M.E., Leverett, P. and Williams, P.A. (2003) - solid

solutions and their significance. CRC LEME Regional Regolith Symposia,

2003. CRC LEME, 78-79.

Clissold, M.E., Leverett, P. and Williams, P.A. (2005) Chemical mineralogy of the

oxidized zones of the E22, E26 and E27 ore bodies at Northparkes, New

South Wales. In: Roach, I.C. (Ed.), Regolith 2005 - Ten Years of CRC LEME,

Proceedings. CRC LEME, 55-58.

Clissold, M.E., Leverett, P., Williams, P.A., Hibbs, D.E. and Nickel, E.H. (2007)

The structure of gillardite, Cu3NiCl2(OH)6, from Widgiemooltha, Western

Australia: the Ni-analogue of herbertsmithite. The Canadian Mineralogist, 45,

317-320.

Colchester, D.M., Leverett, P., Clissold, M.E., Williams, P.A., Hibbs, D.E. and

Nickel, E.H. (2007) Gillardite, Cu3NiCl2(OH)6, a new mineral from the 132

North deposit, Widgiemooltha, Western Australia. Australian Journal of

Mineralogy, 13, 21-24.

viii ABSTRACT

The solution geochemical conditions associated with the development of supergene copper mineralisation in the E22, E26 and E27 deposits at Northparkes,

New South Wales, have been explored. Determination of a stability constant for [NaCaCu5(PO4)4Cl·5H2O], a conspicuous species in the upper oxidised zone of E26, has led to an understanding of the differences between the three deposits in terms of the influence of groundwater geochemistry on their mineralogical diversity. Modelling of copper dispersion from the three deposits using current ground water compositions as proxies for past solution conditions has shown that the elevated chloride concentrations associated with E26 have negligible influence on total dissolved copper concentrations over a wide pH range. The results are discussed with respect to applications in exploration geochemistry for the discovery of new ore deposits in the region.

Determination of a stability constant for lavendulan

[NaCaCu5(AsO4)4Cl·5H2O], the isomorph of sampleite, suggests that solid solution between lavendulan and sampleite is likely to be extensive and this has been established by reference to mineral compositions from a number of deposits.

Activity-activity phase diagrams have been developed to explain the common mineral associates of lavendulan and differences between the analogous phosphate and arsenate systems. With respect to the occurrence of lavendulan in the oxidised zone of the Widgiemooltha 132 N ore body, Western Australia, its crystal chemistry explains why Ni does not substitute for Cu in the lattice. This is despite Ni being abundantly available in the deposit and substituting freely into other copper-based minerals. The substitution of Ni for Cu was explored in a study of supposedly Ni-rich , Cu2Cl(OH)3, from the deposit. It transpires that much of this is a new

ix mineral, gillardite, Cu3NiCl(OH)6, the isomorph of herbertsmithite, Cu3ZnCl(OH)6.

The nature of gillardite was thoroughly investigated and the mineral was approved as a new species by the International Mineralogical Association. A high resolution single-crystal X-ray structure of gillardite has been completed. In addition, the substitution of Ni in simple carbonate lattices has been explored as gaspéite, NiCO3,

Ni-rich magnesite, MgCO3, and , CaCO3, are all common species in the oxidised zone of the Widgiemooltha 132 N deposit.

Attention was subsequently focussed on the geochemistry of the element Bi, with special reference to deposits of the Kingsgate region, New South Wales. This study has led to a modern assessment of the Mo-Bi deposits in the area and new Bi sulfosalts from the Wolfram pipe at Kingsgate are described. A survey of secondary

Bi minerals from a host of deposits has led to the development of a model for the dispersion of Bi in the supergene environment, which will have widespread applications in exploration geochemistry where Bi is used as a pathfinder element.

Calculations of aqueous Bi species in equilibrium with bismite, Bi2O3, ,

BiOCl, and , Bi2O2CO3, over a wide pH range show that the element is very insoluble under ambient oxidising conditions. It is noted that the results of previous geochemical exploration campaigns in the region will have to be reassessed.

x Chapter 1

INTRODUCTION

When primary sulfide deposits that formed deep in the Earth’s crust under comparatively reducing conditions are later exposed to oxidising conditions above the water table, a series of reaction takes place. Many minerals that were stable in the primary environment become thermodynamically unstable in the secondary environment and react. In general the process is one of oxidation and for the most part elements achieve their highest oxidation states (Williams, 1990). New assemblages of secondary minerals can be formed in the oxidised zone above the water table and just which species form depends on the local chemical environment.

In terms of pH and potential, two key physicochemical parameters that describe the geochemical setting of aqueous systems, a remarkably wide range of conditions may develop. These span the whole range of the redox stability of water as defined by equations (1.1) and (1.2) (Appelo and Postma, 1993; Garrels and

Christ, 1965).

+ - O2(g) + 4H (aq) + 4e ⇋ 2H2O(l) (1.1)

+ - H (aq) + e ⇋ 1/2H2(g) (1.2)

The range of achievable pH conditions has its own special limits. Oxidation of ,

3+ FeS2, and the subsequent hydrolysis of Fe (aq) generates sulfuric acid as shown in equations (1.3) to (1.5).

1 2+ 2- + FeS2(s) + 7/2O2(g) + H2O(l) → Fe (aq) + 2SO4 (aq) + 2H (aq) (1.3)

2+ + 3+ Fe (aq) + 1/4O2(g) + H (aq) → Fe (aq) + 1/2H2O(l) (1.4)

3+ + Fe (aq) + 2H2O(l) ⇋ FeOOH(s, ) + 3H (aq) (1.5)

Subsequent evaporation can give rise to solutions that are up to 6 F (formal) in sulfuric acid. The mineralogical evidence for this is apparent from a consideration of the Fe2O3-SO3-H2O system (Posnjak and Merwin, 1922). The mineral kornelite,

HFe(SO4)2·4H2O, found in certain oxidised assemblages derived from pyrite-rich sulfides, can only crystallise from solution under ambient temperatures and pressures when sulfuric acid concentrations are between about 5 and 7 F. On the basic side of neutral, the limits of the natural environment are more constrained. Carbonate buffering [CO2(g)-CaCO3(s)-H2O(l)] serves to limit the pH of aqueous solutions to

8.3 at 298.2 K and 105 Pa (Appelo and Postma, 1993; Garrels and Christ, 1965).

Higher pH values, up to ca 12.5 are much more rarely met as the result of the hydrolysis of Fe-poor silicates, e.g. the hydrolysis of fayalite as shown in equation (1.6).

2+ o - Mg2SiO4(s) + 4H2O(l) ⇋ 2Mg (aq) + Si(OH)4 (aq) + 4OH (aq) (1.6)

This serves to explain the enormous diversity of secondary mineral assemblages (Anthony et al., 1990, 1995, 1997, 2000, 2003) that form under ambient surface or near-surface conditions. The lower temperatures permit the crystallisation of phases (stable or metastable) that would be unstable at higher temperatures.

In general the oxidised equivalents of primary minerals are much more soluble in aqueous solution and their elements are dispersed from oxidising sulfide

2 ore bodies. This gives rise to a classical zoning (Williams, 1990) from the surface down to the water table characterised by a gossan outcrop composed of chemical resistates and oxyhydroxides of Fe and Mn. Beneath this a leached zone is often encountered, in which base metal ions have been depleted, followed by the so-called

“oxidised zone” where secondary base metal minerals are concentrated. At the water table conditions become reducing and certain elements, notably Cu, Ag and Au, become enriched (the supergene enriched zone). This latter zone has long been recognised and targeted in terms of high grade of a number of elements

(Emmons, 1917).

The detection of the dispersed elements in waters and the regolith forms the basis of geochemical exploration methods used to discover new sources of ores.

Modern methods have their origins in the work of Soviet geoscientists starting around 1930 and then taken up by their western counterparts. Hawkes and Webb

(1962) give a fine review of this early work. It is now highly unusual for any exploration program not to employ geochemical methods. Nevertheless, despite some eight decades of research, the chemistry of element dispersion in the secondary environment is not fully understood and for some elements information is virtually non-existent. To substantiate this claim, one could point to current research effort centred in the Cooperative Research Centre for Landscape Environments and

Mineral Exploration in Australia (http://crcleme.org.au/). Key areas for research for many elements are:

• How they are transported in solution?

• What is their chemical speciation?

• What controls secondary mineral formation, adsorption onto other mineral

surfaces and other processes involving mobilisation and concentration?

3 1.1 AIMS OF THIS STUDY

This thesis explores some aspects of the chemistry of Cu, Bi and Ni in the supergene zone near oxidising ore bodies. It builds on work of others to develop some original contributions to the knowledge of the geochemistry of the above and related elements found in such settings. An underlying theme concerns the apparent simple notion that each secondary mineral found near oxidising systems reflects the chemistry of the solutions from which it crystallised. Thus, by reading the

“geochemical signature”, past geochemical events can be reconstructed using appropriate thermodynamic and equilibrium data. An equilibrium approach was brought to bear on selected systems, to reach a surprising number of conclusions and outcomes. The methodology is not immediately obvious, and so first the problems tackled are outlined and the geochemical outcomes of the study are highlighted.

1.1.1 Northparkes study

A geochemical study of the oxidised zones of porphyry-style Cu-Au deposits at Goonumbla (Northparkes), New South Wales, was undertaken. Both primary and secondary assemblages at Goonumbla have been thoroughly described in the past

(Crane et al., 1998; Heithersay et al., 1990; McLean et al., 2004; Tonui et al., 2002).

In the three ore bodies that have been exploited, E22, E26 and E27, upper oxidised zones are dominated by the secondary Cu(II) phosphate minerals ,

Cu2PO4(OH), and , Cu5(PO4)2(OH)4, and, uniquely to E26, the otherwise rare mineral sampleite, NaCaCu5(PO4)4Cl·5H2O. The reason for the abundance sampleite in E26 has been traced to its emplacement under rather more saline (NaCl) conditions than those in other two deposits. The determination of a

o value for the standard free energy of formation (ΔfG ) of sampleite at 298.2 K was a

4 key to understand the chemical evolution of the secondary copper mineralisation of the region. By using current ground water compositions as proxies for ground waters of the past it became possible to reconstruct the geochemical history of the mineralising supergene environment of previous times. In particular, an assessment of copper dispersion in the different (saline) settings helped to discern whether they influence dissolved copper loadings. Little difference is evident from modelling aqueous solution chemistries, which implies that the supergene geochemical

“footprint” of the systems is independent of ground water compositions. The system was compared with other deposits rich in secondary copper (Chapman et al., 2005; Crane et al., 2001) to provide an explanation for the origin of the that blankets the Goonumbla deposits provided. The conclusions of the study have been incorporated in the geochemical exploration strategy of Northparkes

Mines.

1.1.2 Lavendulan study

Lavendulan, NaCaCu5(AsO4)4Cl·5H2O, is the arsenate isomorph of sampleite

o (Giester et al., 2007). A value for ΔfG of lavendulan at 298.2 K has also been determined. The value suggests that solid solution between lavendulan and sampleite is likely to be extensive and this was established by reference to mineral compositions from a number of deposits. The incorporation of Pb for Ca in the lattice was explored. In terms of known mineral species, the CuO-As2O5-H2O system is more complex than the CuO-P2O5-H2O system and this was investigated in terms of the different mineral associates of lavendulan reported in the literature (Birch, 1990;

Giester et al., 2007; Guillemin, 1956; Kleeman and Milnes, 1973; Kokinos and Wise,

1993; Nickel et al., 1994; Ryall and Segnit, 1976; Segnit, 1976). An interesting

5 feature of the extent of the stability field of lavendulan in relation to that of sampleite is that lavendulan is restricted by conditions that give rise to a common associate, , CaCuAsO4(OH). Conichalcite has no phosphate counterpart. However, lavendulan is found more commonly than sampleite as a result of the generation of arsenate during the oxidation of common As-bearing sulfide ores.

In regard to lavendulan in the Widgiemooltha 132 N deposit, Western

Australia (Nickel et al., 1994), its crystal chemistry (Giester et al., 2007) explains why Ni does not substitute for Cu in the lattice. This is despite Ni being abundantly available in the deposit and substituting freely in magnesite, MgCO3, calcite, CaCO3, and other secondary copper minerals. An assessment of the energetics of these systems was made.

The substitution of Ni for Cu was further appraised in a study of Ni-rich paratacamite, Cu2Cl(OH)3, R3 (Fleet, 1975), from the Widgiemooltha

132 N deposit (Nickel et al., 1994). The material is now a new mineral, approved by the IMA as gillardite (Colchester et al., 2007). Gillardite is rhombohedral, space group R3 m, and has an ideal stoichiometry of Cu3NiCl2(OH)6. Its single-crystal X- ray structure was determined (Clissold et al., 2007) and it is the Ni-analogue of herbertsmithite, Cu3ZnCl2(OH)6 (Braithwaite et al., 2004).

1.1.3 Kingsgate Bi study

Attention was focussed on the geochemistry of the element Bi, with special reference to deposits of the Kingsgate region, New South Wales. This led to a modern assessment of the Mo-Bi deposits situated south of the Yarrow River

(Andrews, 1916; Garretty, 1943, 1944a,b), and new Bi sulfosalts from the Wolfram pipe on the main field are described. A survey of the relative frequency of occurrence

6 of secondary Bi minerals from a host of deposits was made to determine which phases are important in developing a model for the dispersion of Bi in the supergene environment. For the first time, a coherent chemical explanation for Bi mobility has been outlined, based on the solution chemistry of the element and the stabilities of bismite, Bi2O3, bismutite, Bi2O2CO3, and bismoclite, BiOCl.

The ramifications of the model in terms of past exploration geochemical campaigns (MacDuff and Snow, 1971; MacDuff and Zerwick, 1971a,b, 1972) are discussed and ways to elaborate it outlined. The model will have widespread applications in exploration geochemistry where Bi is used as a pathfinder element

(Hale, 1981; Lang and Baker, 2001; Leverett et al., 2004; Lueth, 1999). The usefulness of the model is reflected in its adoption in both regional and local geochemical exploration in the New England region of New South Wales by

Auzex Resources Limited.

7 Chapter 2

GEOCHEMICAL EVOLUTION OF THE OXIDISED

ZONES OF THE COPPER ORE BODIES AT

NORTHPARKES, NEW SOUTH WALES, AND ITS

RELEVANCE FOR GEOCHEMICAL EXPLORATION

2.1 SETTING

Geopeko Wallsend Operations Ltd discovered several porphyry copper-gold deposits at Northparkes in central New South Wales (Figure 2.1.1) in 1977, during a regional reconnaissance drilling survey. They are associated with finger-like bodies of 430-440 Ma -monzonite porphyries, which intrude the Ordovician age

Goonumbla Volcanics (Heithersay et al., 1990). Disseminated, - and vein- controlled mineralisation occurs in the monzonite and the volcanics, but is focussed on quartz stock work veining associated with the monzonite. The major primary minerals are pyrite, bornite and , together with economically significant native gold. Minor amounts of primary digenite, chalcocite, galena, sphalerite, , , gersdorffite, calaverite, and other tellurides and selenides are also present. Sphalerite and galena occur in quartz veins associated with a later faulting event. Quartz is the only significant gangue mineral. Both primary and secondary ores from three pipe-like bodies, E22, E27 and E26 North (E26) have been worked for copper and gold by Northparkes Mines since 1994.

8

Figure 2.1.1. Location of the Northparkes deposits, NSW (ca 32o 55′S, 148o02′E).

Outcrop is poor over the three deposits, which are covered by a mixture of clays, some of which are in situ weathering products, and transported overburden

(Arundell, 2004; Heithersay et al., 1990). The base of oxidation extends up to 80 m from the surface, with strong kaolinisation of the monzonite from approximately 5 to

45 m below surface. There is little evidence of gossan development over the deposits, owing to the disseminated nature of the primary mineralisation. The region has experienced a prolonged and episodic cycle of weathering. Saprolite and transported sediments over E22 and E27 have been dated using paleomagnetic methods and two significant weathering events have been identified, one in the Carboniferous at around 325 Ma, and another in the Cainozoic, from about 60 Ma and presumably

9 continuing to the present (O'Sullivan et al., 2000; Pillans et al., 1999). The latter is one of two major periods of comparatively recent weathering around Australia, the other occurring around 12-16 Ma (McQueen et al., 2002; Pillans, 2004); the latter reference concentrates on the weathering history of the neighbouring Cobar region.

As a result of weathering, E22, E26 and E27 deposits display well-developed oxidised zones, with intense leaching of the upper sections giving rise to pervasive kaolinite development, especially in E22 and E27 (Crane et al., 1998; McLean et al.,

2004; Tonui et al., 2002). Upper oxidised zones are dominated by the secondary

Cu(II) phosphate minerals libethenite (Cu2PO4(OH)) and pseudomalachite

(Cu5(PO4)2(OH)4) and, uniquely to E26, sampleite (NaCaCu5(PO4)4Cl·5H2O). In

E26, this phosphate-rich zone came closer to the surface and the three phosphate minerals are common in material removed from the top of the ore body prior to block caving operations. Beneath the phosphates a zone dominated by malachite

(Cu2CO3(OH)2), azurite (Cu3(CO3)2(OH)2) and chrysocolla (ca CuSiO3·nH2O), the former carrying coarse secondary gold, gave way at depth to a thin native copper- (Cu2O)-chalcocite (Cu2S) supergene enriched zone. Chrysocolla is less abundant in E26. Again, E26 is exceptional in that the formation of the secondary

Cu(II) carbonates was preceded by extensive deposition of atacamite (Cu2Cl(OH)3).

A controlling factor in the development of the very different oxidised zone in E26 to those in E22 and E27 is groundwater composition; this is reflected in turn by the compositions of present ground waters (McLean et al., 2004), with those associated with E26 being much more saline (NaCl).

This research has focussed on the reconstruction of the solution conditions associated with the formation of oxidised base metal ores and the control that they may exert on the dispersion of metallic elements and hence on geochemical

10 anomalies in the regolith. A study of the New Cobar deposit (Leverett et al., 2004) showed that this approach could be applied to explain how elements were differentially mobilised during oxidation of sulfides and the relative extent of their transport away from primary ore zones. This study extends this approach to the deposits at Northparkes and discusses its application in exploration geochemistry.

Comparison is made with the oxidised zone uncovered in the main pit at

Girilambone, New South Wales (Chapman et al., 2005; Fogarty, 1998; Shields,

1996). In order to model the environment of deposition in E26, a stability constant for sampleite at 298.2 K was determined. This bears on the development of the secondary Cu(II) phosphates in an acid, saline environment.

2.2 EXPERIMENTAL

2.2.1 Instrumentation

Powder X-ray diffraction (XRD) measurements were carried out using a

Philips PW1925-20 powder diffractometer (Cu Kα radiation with pure Si as internal standard). Complementary analyses, where appropriate, were carried out using a

JEOL JXA 840 microanalyzer scanning electron microscope (SEM) equipped for energy-dispersive X-ray analysis (EDAX), or a total reflectance X-ray fluorescence

(XRF) instrument of in-house design using an optically flat quartz sample support,

Mo Kα radiation and an Amptek XR-100CR Peltier-cooled X-ray detector. Electron microprobe analyses were carried out using a JEOL JXA-8600 electron microprobe analyzer equipped with wavelength dispersive spectrometers, analysing from Be to

U, and a Kevex energy dispersive spectrometer, analysing from Na to U. Atomic absorption spectrophotometry (AAS) measurements (Cu) were carried out using a

Perkin Elmer AAnalyst 100 instrument using matched standards consisting of

11 -3 CuCl2·2H2O in 0.1 mol dm NaCl prepared using pre-calibrated glassware. A

Radiometer PHM 93 meter fitted with an IJ44 combination electrode was used for pH measurements.

2.2.2 Synthesis

Pure sampleite was synthesised as follows. CaCl2 (0.1110 g, 1 mmol),

CuCl2·2H2O (0.8520 g, 5 mmol), Na2PO4 (0.5678 g, 4 mmol) and NaCl (5.843 g, 0.1 mol) were added to a Teflon-lined Parr acid digestion bomb together with 75 cm3 of deionised water. The bomb was heated to 100oC for 48 hours and then cooled slowly to room temperature. The product was collected at the pump, washed with water, then acetone, and sucked dry. Use of lesser amounts of NaCl resulted in mixtures of sampleite and libethenite. Gram quantities of sampleite were easily obtained using the above procedure. No other phases were detected in the product using XRD and satisfactory analyses corresponding to the stoichiometric formula were obtained.

2.2.3 Solution studies

Preliminary studies showed that sampleite dissolves incongruently in aqueous

10-3 mol dm-3 HCl solution to give mixtures of sampleite and libethenite. However, the mineral does dissolve congruently in aqueous 10-3 mol dm-3 HCl solution that is also 0.1 mol dm-3 in NaCl. Excess solid sampleite was equilibrated in several sealed flasks with 100 cm3 of aqueous 10-3 mol dm-3 HCl plus 0.1 mol dm-3 NaCl. The flasks were placed in a shaking water bath and maintained at 25 ±0.1oC. Parallel experiments were conducted to monitor pH changes as the solutions reached equilibrium with sampleite. No pH change was observed after two weeks, but solutions were kept in the water bath for a further ten weeks. At this time, the pH of

12 each solution was recorded and the sample filtered through a 0.2 m fibreglass disc prior to measurement of total dissolved Cu. For the six experimental runs undertaken, total dissolved Cu concentrations (x 10-4 mol dm-3) with the equilibrium pH values in parentheses were 6.07(4.551), 5.95(4.550), 6.18(4.550), 6.25(4.551),

6.18(4.551) and 6.01(4.550). This to a solubility of sampleite,

-4 -3 NaCaCu5(PO4)4Cl·5H2O, of 1.22 ±0.03 x 10 mol dm at 298.2 ±0.1 K and a pH of

4.550 ±0.001.

In order to calculate a stability constant for sampleite, a species distribution calculation using the average solubility of the mineral was carried out, together with similar calculations that took into account the error in the solubility. Species incorporated in the COMICS calculations (Perrin and Sayce, 1967) were Na+, Ca2+,

2+ 3- 2- - o - + + o + Cu , PO4 , HPO4 , H2PO4 , H3PO4 , Cl , CuOH , CaOH , CaHPO4 , CaH2PO4 ,

+ o + CuCl , CuHPO4 , and CaH2PO4 . Stability constants (Martell and Smith, 1982;

Smith and Martell, 1976, 1989) were corrected to an ionic strength of I = 0.102 mol dm-3 (shown in Table 2.2.3.1) using the Davies modification of the Debye-Hückel equation, taking γ for neutral species to be equal to unity, at 298.2 K (lgγi = -

2 ½ ½ 0.5085zi [I /(1 + I ) –0.3I], where zi is the charge on species i. Calculated

Table 2.2.3.1 Equilibrium constants for complex species when I = 0.1 used in determining species distributions. Species Log K CuOH+ -8.02 CaOH+ -13.02 2- HPO4 11.85 - H2PO4 18.67 o H3PO4 20.78 o CaHPO4 13.73 + CaH2PO4 19.64 CuCl+ -0.03 o CuHPO4 15.17 + CuH2PO4 19.98 Values calculated from Martell and Smith (1982); Smith and Martell (1976, 1989).

13

+ 2+ 2+ - equilibrium concentrations of the free aquated ionic species Na , Ca , Cu , H2PO4 and Cl- were 0.1001, 1.212 x 10-4, 5.503 x 10-4, 4.537 x 10-4 and 0.1011 mol dm-3, respectively, for the average solubility of sampleite at pH 4.550. These values, together with lgγ± = -0.108 and lgγ2± = -0.430 (I = 0.102 mol dm-3) were used in turn to calculate KH, with respect to the equations below, where a(i) is the activity of species i (a(i) = m(i)γ(i), with m(i) being the concentration of species i).

+ + 2+ 2+ NaCaCu5(PO4)4Cl·5H2O(s) + 8H (aq) ⇋ Na (aq) + Ca (aq) + 5Cu (aq)

- - + 4H2PO4 (aq) + Cl (aq) + 5H2O(l) (2.1)

+ 2+ 2+ 5 - 4 - + 8 KH = a(Na )a(Ca )a(Cu ) a(H2PO4 ) a(Cl )/a(H ) (2.2)

At 298.2 K, lgKH is equal to –2.42 ±0.47. From this result,

o -1 ΔfG (NaCaCu5(PO4)4Cl·5H2O,s,298.2K) = -6342.8 ±7.4 kJ mol . With respect to this quantity, values for the free energies of formation of component ions and water

- were taken from Robie and Hemmingway (1995), except for H2PO4 (aq). The value

- -1 used for H2PO4 (aq) at 298.2 K (-1130.6 ±0.9 kJ mol ) was derived from a value for

3- the corresponding PO4 (Robie and Hemingway, 1995), together with the first and second proton association constants given by Smith and Martell (1976). The total error in ΔfGo for sampleite was calculated by the addition of the errors for individual species (Robie and Hemingway, 1995) and the calculated error in log KH. It is noted that no error is listed for ΔfGo for Ca2+(aq) and this is estimated to be 0.1 kJ mol-1.

14 2.3 GEOCHEMISTRY OF DEVELOPMENT OF THE OXIDISED

ZONES AT NORTHPARKES

2.3.1 Phosphate minerals

The oxidised zones at Northparkes developed as a result of a series of discontinuous events. Secondary Cu(II) phosphates are present in the upper sections of all three oxidised zones and represent an early phase of mineralisation.

Thermodynamic data are available for libethenite, pseudomalachite and cornetite

(Cu3PO4(OH)3), although the last is not observed at Northparkes (Magalhães et al.,

1986, 1988), and the conditions under which they form has been explored (Crane et al., 2001). Thermodynamic data for associated phosphate minerals have been listed in Table 2.3.1, along with similar data for relevant dissolved species.

Figure 2.3.1 shows that libethenite, common to all three oxidised zones at

Northparkes, can only form with elevated activities of dissolved phosphate species and at rather low pH values at 298.2 K. The diagram was constructed using a value for a(Na+) equal to that of the chloride ion, and 10 times that of the

Table 2.3.1. ΔfGº (298.2 K) for minerals and dissolved species used in geochemical modelling calculations. Species Formula ΔfGº(kJmol-1) Sourcea Cu3(PO4)2 -2051.3 1 Libethenite Cu2PO4(OH) -1224.4 ± 3.2 1 Pseudomalachite Cu5(PO4)2(OH)4 -2832.8 ± 5.0 1 Cornetite Cu3PO4(OH)3 -1603.0 ± 2.8 1 Conichalcite CaCuAsO4(OH) -1471.7 ± 3.3 1 Atacamite Cu2Cl(OH)3 -667.55 1 Sampleite NaCaCu5(PO4)Cl·5H2O -6342.8 ± 7.4 2 Cu2+ +65.1 3 Ca 2+ -553.6 3 Na+ -261.5 3 Cl- -131.2 3 - H2PO4 -1130.61 4 a[1] Williams (1990); [2] this study; [3] Robie and Hemingway (1995); [4] Robie and Hemingway (1995); Smith and Martell (1976).

15 23456789pH

Sampleite - -6 NaCl saturation a (H2PO4 )= 10

Atacamite 0 - -5 a (H2PO4 )= 10

- -4 a (H2PO4 )= 10 ) - -2 (Cl a lg

Pseudomalachite Cornetite

-4 Libethenite

-6

Figure 2.3.1. Relationships between the secondary copper(II) minerals at 298.2 K. The diagram was constructed using a value for a(Na+) equal to that of the chloride ion, and 10 times that of the calcium ion (see text). While an atacamite field is - expressed at the lowest H2PO4 activity, its crystallisation would only occur at untenably high Cu2+ activities (it is soluble at low pH).

ion (approximately in line with the current groundwater geochemistry associated with E26; see below). Thermochemical data for water and dissolved ions were taken from the literature (Martell and Smith, 1982; Robie and Hemingway, 1995; Smith and Martell, 1976, 1989).

In order to mobilise sufficient phosphate for this to occur, mineralising solutions must be acidic enough to begin to dissolve accessory fluorapatite

(Ca5(PO4)3F). Data for fluorapatite (Robie and Hemingway, 1995) indicate that this is only feasible under acidic conditions, most probably associated with the oxidation

16 of sulfides, and the hydrolysis of Fe(III) to form goethite, as illustrated in equation

(2.3) below for the reaction of pyrite.

+ 2- FeS2(s) + 15/4O2(g) + 5/2H2O(l) → FeOOH(s) + 4H (aq) + 2SO4 (aq) (2.3)

As protons were consumed by reaction with, for example, feldspars to give clays (see equations below; similar reactions may be written for and other silicate phases, with forming as an intermediate), particularly kaolinite, leached copper and phosphate would react to form libethenite and pseudomalachite in turn.

The latter phase is stable over a much wider range of pH and phosphate activities and is relatively abundant in all the Northparkes upper oxidised zones. Additional evidence for the neutralisation of acidic phosphate-bearing solutions with time is found in the crystallisation of late secondary hydroxylapatite on libethenite and pseudomalachite in E22 and E27 (Crane et al., 1998).

+ + 3KAlSi3O8(s) + 12H2O(l) + 2H (aq) → KAl3Si3O10(OH)2(s) + 6Si(OH)4(aq) + 2K (aq) orthoclase illite (2.4)

+ + 2NaAlSi3O8(s) + 9H2O(l) + 2H (aq) → Al2Si2O5(OH)4(s) + 4Si(OH)4(aq) + 2Na (aq) albite kaolinite (2.5)

+ 2+ CaAl2Si2O8(s) + H2O(l) + 2H (aq) → Al2Si2O5(OH)4(s) + Ca (aq) anorthite kaolinite (2.6)

In addition, the release of dissolved silicic acid during kaolinisation of the leached zones at Northparkes as protons are consumed is mirrored in the deposition of secondary quartz endomorphs enveloping libethenite (Crane et al., 1998). Formation

17 of secondary barite (BaSO4) early in the paragenetic sequence in E22, E26 and E27

(Crane et al., 1998; McLean et al., 2004) is further evidence of a low pH regime at this stage. While the source of Ba2+ ions probably also involves the decomposition of feldspars and micas, transport of significant amounts of barium and ions in solution at ambient temperatures requires conditions acidic enough to form

- appreciable concentrations of HSO4 , together with ionic strengths high enough to

2+ 2- have an effect on lowering the activity coefficients of Ba (aq) and SO4 (aq)

(Blount, 1977). A subsidiary mechanism to generate locally high activities of dissolved phosphate species and copper ion could have involved the well-understood adsorption of Cu2+ and phosphate on iron and manganese oxides (Arai and Sparks,

2001; Post, 1999; Sparks, 2001). It is noted in this connection that much of the libethenite and pseudomalachite of the three deposits is associated with goethite and

Mn-rich oxides at the base of the leached zones (particularly in E22 and E27). As poorly-crystalline precursors of goethite and the like recrystallised to more stable phases, copper and phosphate would be released from cryptocrystalline surfaces to react essentially in situ. Nevertheless, the emplacement of libethenite and pseudomalachite requires a low pH regime, under which secondary phases such as malachite, azurite and atacamite are freely soluble.

In conjunction with the above phenomena, extensive crystallisation of sampleite in the oxidised zone of E26 took place (Figure 2.3.2). For this to occur, both elevated phosphate and chloride activities are necessary. Figure 2.3.1 also illustrates the conditions that must be satisfied for sampleite to form at 298.2 K, using the stability constant for sampleite reported above and that for atacamite from

- -4 the literature (Smith and Martell, 1976; Williams, 1990). For a(H2PO4 ) = 10

- (H2PO4 is the dominant phosphate solution species at pH values between about 2 and

18 - -2 - -6 - 7), a(Cl ) must be greater than 10 and with a(H2PO4 ) = 10 , necessary a(Cl ) values need to approach those associated with saturated NaCl solutions. The rarity of sampleite (Anthony et al., 2000) is thus seen as a consequence of the rather unusual solution conditions required for its crystallisation. In this connection it is possible to

- estimate both pH and a(H2PO4 ) conditions that prevailed during the sampleite mineralisation event. As noted above, dissolved phosphate species are derived from fluorapatite, which dissolves incongruently to form fluorite (Misra, 1999) as shown in the equation below.

+ 2+ - 2Ca5(PO4)3F(s) + 12H (aq) ⇋ CaF2(s) + 9Ca (aq) + 6H2PO4 (aq) (2.7)

o -1 At 298.2 K, ΔrG = +38.1 kJ mol and lgKH = -6.673

2+ 9 - 6 + 12 (KH = a(Ca ) a(H2PO4 ) /a(H ) ) for the reaction based on the data of Robie and

Hemingway (1995). As a first approach, it is convenient to ignore activities and to treat the reaction in terms of concentrations. From stoichiometric relationships,

2+ - - [Ca ] = 9/6[H2PO4 ], and the lgK expression can thus be recast as lg[H2PO4 ] = -

- 0.551 – 0.8 pH. For pH = 3, 4, 5 and 6, lg[H2PO4 ] = -2.95, -3.75, -4.55 and -5.35, respectively. These results are quite consistent with those that may be abstracted

- from Figure 2.3.1. To preclude formation of atacamite, a(H2PO4 ) would need to be of the order of 10-5 and the pH thus less than 5. For libethenite to form, as observed in the zone of sampleite crystallisation (Figures 2.3.2 and 2.3.3), the pH must locally have fallen below 3. Figure 2.3.1 indicates an activity of Cl- of the order of 0.1 for the above conditions. However, a more realistic set of solution parameters can be deduced on the basis of current groundwater geochemistry. This is because Ca2+ is contributed, of course, from sources other than fluorapatite alone.

19 500 µm

Figure 2.3.2. Secondary electron image of sampleite and libethenite from Northparkes E26 deposit, NSW.

500 µm

Figure 2.3.3. Secondary electron image of libethenite from Northparkes E26, NSW.

20 Taking note of the absence of sampleite in E22 and E27, it is apparent that present day groundwater compositions reflect mineralogical differences in the oxidised copper assemblages at Northparkes. Table 2.3.2 lists data for three high- quality analyses of ground waters associated with E22 and E26. It is particularly noteworthy that the two samples from E26 have chloride concentrations over a magnitude greater than the sample from E22. Ca2+ activities have been calculated

- from the data and are listed in Table 2.3.2. Calculation of values of a(H2PO4 ) can be made directly using the KH value for the acid dissolution of fluorapatite. For sample

- E26P118, lga(H2PO4 ) = -3.86, -5.86, -7.86 and -9.86 for pH 3, 4, 5 and 6, respectively. Corresponding values for sample E26P119 are

- lga(H2PO4 ) = -3.73, -5.73, -7.73 and -9.73, for the same pH conditions, and for

- sample E22P157, lga(H2PO4 ) = -3.07, -5.07, -7.07 and -9.07, respectively. Similar corrections for activity coefficients give values of lga(Cl-) of -0.62 and -0.60 for E26 and -1.67 for E22 (Table 2.3.2). Reference again to Figure 2.3.1 indicates that with

- -5 respect to the former an a(H2PO2 ) of less than 10 in the presence of suitable amounts of Na+ and Ca2+ will cause the crystallisation of sampleite, whereas for the

- -4 E22 case, a(H2PO2 ) must be somewhat greater than 10 . Evidently, this higher value was not achieved and sampleite is thus absent in both E22 and E27 deposits.

Furthermore, the calculations fix the pH of mineralising solutions in E26 during the phosphate phase at between 3 and 4. This low pH regime is quite consistent with the oxidation of sulfides in a poorly buffered environment and serves to explain other features of the deposits at Northparkes. Leaching of the upper oxidised zones is extensive and the phosphate minerals are not accompanied by any other Cu(II)

21 Table 2.3.2. Groundwater analyses (concentrations in mol dm-3 except for pH) for E22 and E26 deposits.a Sample numberb E26P118 E26P119 E22P157 pH 7.25 6.85 7.80 carbonate negc neg 0.00002 bicarbonate 0.00338 0.00439 0.00336 chloride 0.32550 0.34581 0.02651 sulfate 0.03643 0.03940 0.00588 potassium 0.00046 0.00049 0.00015 0.26925 0.28447 0.01544 calcium 0.01884 0.02445 0.00474 magnesium 0.04422 0.04566 0.00823 Σ(+) 0.39583 0.42518 0.04153 Σ(-) 0.40176 0.42900 0.04163 I 0.50 0.54 0.06 γ± 0.737 0.726 0.806 γ2± 0.295 0.278 0.432 lg a(Cl-) -0.62 -0.60 -1.67 lg a(Ca2+) -2.255 -2.167 -2.697 aAnalytical data originally reported in ppm; data are reliable to three significant figures and extended values are only the result of calculations to change concentration units. bE26P118 and E26P119 samples from beneath the E26 deposit and E22P157 from E22. cNot detectable.

phases to a significant extent. The reason for this is that the latter are simply too soluble at this pH to be precipitated. To illustrate this phenomenon, reference is made to equilibrium conditions between sampleite and pseudomalachite, in the equation below.

+ 2+ NaCaCu5(PO4)4Cl.5H2O(s) ⇋ Cu5(PO4)2(OH)4(s) + Na (aq) + Ca (aq)

- - + 2H2PO4 (aq) + Cl (aq) + H2O(l) (2.8)

- Use of the data of Table 2.3.2 gives for E26 lga(H2PO4 ) = ca -4, and a pH of ca 3.1.

In turn, a(Cu2+) is derived from (2.2) as being about 0.03. Inspection of the data of

Table 2.3.2 for this level of dissolved copper indicates a deficiency in anion concentrations and these must be accounted for. However, it is possible to deduce what these would have been, and it leads to a somewhat surprising outcome. First,

22 extra chloride would be a component, now incorporated in subsequent atacamite mineralisation. More significant, however, would be sulfate released during the oxidation of sulfides, together with the copper in solution that was to some extent incorporated in the Cu minerals of the oxidised and supergene enriched zones. As protons reacted with host rocks, particularly feldspars, to form clays, the overall exchange process was of protons for potassium, sodium and, particularly, calcium ions [c.f. equations (2.4) to (2.6)]. A feature of the profiles at Northparkes is the pervasive development of gypsum at a level somewhat below the water table

(Heithersay et al., 1990). This then is seen as a natural consequence of the weathering of both sulfides and host rock silicates during the development of the oxidised zone. It is noted that the layer of gypsum impregnation is not geologically controlled, but parallels surface topography (Heithersay et al., 1990). Gypsum is rather slow to nucleate from supersaturated solution (see for example, Abdel-Aal et al., 2004; Lancia et al., 1999; van der Ende, 1991) and its precipitation at lower levels reflects this, at least in part.

As aqueous phosphate activities fell (with an accompanying and necessary rise in pH), solution conditions evolved to be consistent with those associated with the continuing formation of pseudomalachite and, with the essential exhaustion of available phosphate, subsequent crystallisation of atacamite in E26. Pseudomorphs of atacamite, chrysocolla and, more rarely, pseudomalachite after sampleite are noted in the oxidised zone of E26 (McLean et al., 2004) and lend further support to the evolution of oxidising conditions with time. The basic copper(II) phosphates are rather slow to dissolve at ambient temperatures (Crane et al., 2001) and their preservation is no doubt due to this in part.

23 The fact that both high chloride and phosphate activities play key roles in the formation of sampleite is a key to understanding its absence in other deposits where the more common secondary Cu(II) phosphates libethenite and pseudomalachite are found. At Girilambone, New South Wales, abundant secondary libethenite and pseudomalachite mineralisation is associated with supergene mineralisation in the main pit (Chapman et al., 2005) and sampleite is absent. High-quality analyses of some 13 groundwater samples adjacent to the main pit and three satellite deposits

(Northeast, Hartmans, and Larsens) are available (Elvy, 1998). Full speciation calculations for these give a(Cl-) values ranging from 0.055 to 0.156. Values of

- a(H2PO4 ), however, are much lower, ranging from less than measurable to

4.39 x 10-7. In line with Figure 2.3.1, the absence of sampleite in the deposits is readily explained. Sampleite from the type locality at Chuquicamata, Chile (Cook,

1978), has an association similar to that found at Northparkes. Accompanying phases are atacamite (Figure 2.3.4), libethenite and . The former is indicative of high chloride activities and the latter two of an acidic environment. These observations are

Figure 2.3.4. Sampleite associated with atacamite from Northparkes E26 deposit.

24 quite consistent with the conclusions drawn above, based on the determined stability constant for sampleite.

2.3.2 Atacamite, malachite and azurite

Atacamite deposition in E26 took place after the phosphate suite had developed and was emplaced higher in the oxidised zone than secondary copper carbonates. In some places, atacamite is associated with malachite and azurite, but much material containing the secondary carbonates contains no halide minerals.

Instead, it is often associated with cuprite and native copper (McLean et al., 2004), indicating that it came from the lower oxidised zone. It is noteworthy that only traces of clinoatacamite, the thermodynamically stable polymorph of composition

Cu2Cl(OH)3, are present at Northparkes. This is a consequence of the inhibition of nucleation of clinoatacamite when excess Cl-(aq) is present (Pollard et al., 1989).

Under the conditions that prevailed at Northparkes in E26, the metastable polymorph persisted, in line with present groundwater compositions (Table 2.3.2). Development of atacamite is the consequence of a second secondary Cu mineralisation event, when dissolved phosphate species had essentially been exhausted, as pH rose when protons reacted with feldspars and the like. The development of atacamite versus malachite or azurite is dictated by the prevailing pH of mineralising solutions, the availability of chloride ions, and variation of the partial pressure of CO2(g). Figure 2.3.5 illustrates relationships between atacamite, malachite and at 298.2 K, at a

-3.5 p(CO2) value of 10 , corresponding to atmospheric concentrations. Atacamite encroaches on the stability fields progressively as a(Cl-) increases. With respect to

E26, for a value of lga(Cl-) = -0.6 (Table 2.3.2), brochantite can only form when

2- -1 a(SO4 ) is greater than about 10 . This is consistent with the data of Table 2.3.2, in that brochantite is very rare in E26 (McLean et al., 2004).

25 23456789pH 0

Brochantite

-2

) -4 2- 4 (SO

a Malachite/ Azurite

lg -6

-8 Atacamite

10-4 10-3 10-2 10-1 10-0.6 a (Cl-) -10

Figure 2.3.5. Relationships between atacamite, malachite and brochantite at 298.2 K, -3.5 with a p(CO2) value of 10 (corresponding to atmospheric concentrations).

Figure 2.3.6 illustrates stability relations between atacamite, malachite and azurite with varying partial pressures of CO2(g) at 298.2 K. Boundaries are between

-1.36 atacamite and malachite up to a p(CO2) value of 10 . This p(CO2) is the equilibrium partial pressure at 298.2 K for reaction given below, when malachite

-1 coexists with azurite. At p(CO2) = 10 , azurite is the stable secondary carbonate.

3Cu2CO3(OH)2(s) + CO2(g) ⇋ 2 Cu3(CO3)2(OH)2(s) + H2O(l) (2.9)

26 345678pH 0

Atacamite

-1 Azurite

-2 ) -

-1 (Cl -3 10 a -1.36

lg 10

-4

10-2.5 Malachite

-5

10-3.5

p (CO2) -6

Figure 2.3.6. Relationships between atacamite, malachite and azurite with varying partial pressures of CO2(g) at 298.2 K. Boundaries are drawn with respect to -1.36 atacamite and malachite up to a p(CO2) value of 10 . At p(CO2) values higher than 10-1.36, azurite is the stable secondary carbonate.

Primary mineralisation at Northparkes contains small amounts of carbonate (Tonui et al., 2002), but a likely source for the considerable amounts fixed in malachite-azurite mineralisation is apparent from stable carbon measurements of azurite from E27. A value of 13C = -11.23 indicates a significant biological input (Melchiorre and

Enders, 2003). With pH ranging of between 4 and 8, and lga(Cl-) = -0.6 (Table

-3.5 -1 2.3.2), as p(CO2) increased from, say, 10 to 10 , conditions pass progressively from those that would give rise to atacamite to those associated with malachite and azurite formation in turn. This simple geochemical picture serves to explain how all of the major copper(II) minerals developed in E26 (and E22 and E27); in addition, it

27 illustrates why phases common in other settings are not seen. While continuously evolving chemical conditions may have prevailed during the passage from atacamite to carbonate deposition, this too may have been episodic. It is not possible at this stage to relate the phosphate, chloride and carbonate events to the major paleoweathering ages for Northparkes. However, the overall phosphate → chloride

→ carbonate sequence is clearly indicated by the phase relationships described above, together with field relationships (McLean et al., 2004).

2.4 GEOCHEMICAL DISPERSION OF COPPER FROM THE

OXIDISED ZONES AT NORTHPARKES

Leverett et al. (2004) described a method for estimating the extent of element mobility in ground waters at the New Cobar deposit, based on a reconstruction of groundwater compositions. This was possible in the light of the secondary mineral assemblage at the deposit. As far as Northparkes is concerned, present day groundwater compositions are evidently good proxies for previous groundwaters as far as major cations and anions are concerned, as they are consistent with a formal description of the development of the oxidised zones using equilibrium approaches; this has been dealt with in detail above. The approach here was to derive a set of starting parameters for minor aqueous species for the chloride and carbonate events, taken separately, and to use the current groundwater compositions to derive total dissolved copper concentrations in equilibrium with the assemblages. This follows the New Cobar approach, but in this case is much simpler because copper is the only base metal present in any significant amount. As far as the phosphate mineralising event is concerned, the low pH values associated with it indicate that significant copper was dispersed. For the atacamite and malachite/azurite events, solution

28 chemistry is more subtle at higher pH values and calculations were carried out to determine effects on copper dispersion of these two styles of mineralisation.

Calculations of total dissolved copper in equilibrium with azurite, malachite and atacamite were carried out for pH values of 5, 6 and 7, and for p(CO2) values of 10-3.5 (atmospheric), 10-2.5 (typical soil gas levels) and 10-1.36 [equilibrium pressure of CO2(g) at 298.2 K with respect to equation (2.9)]. It is noted that both secondary carbonates were abundant in all lower oxidation zones (Crane et al., 1998;

McLean et al., 2004). Stability constant data for dissolved carbonate species,

+ o 2- + o CuHCO3 , CuCO3 , Cu(CO3)2 , CuCl and CuSO4 , and malachite and azurite were taken from the literature (Martell and Smith, 1982; Smith and Martell, 1976, 1989;

Williams, 1990; Zirino and Yamamoto, 1972). The concentrations of these species and of Cu2+(aq) were calculated using the ground water concentrations of Table 2.3.2 for all other species. Corrections to activities were made in the usual way and total copper concentrations summed. Results are listed in Table 2.4.1. For the E26 calculations, reference to Figure 2.3.6 indicates that the stable phase to be taken into

-1.36 account is atacamite in all cases except when pH = 7 and p(CO2) = 10 , when it is malachite or azurite. In the case of the E22 sample, azurite is the stable phase except

-1.36 - at pH = 7 and p(CO2) = 10 , when again it is malachite or azurite. At p(CO2) = 10

3.5 and pH = 5, total dissolved copper concentrations for the two E26 and the E22 ground water analyses are 3.66 x 10-3, 3.74 x 10-3 and 4.07 x 10-2, respectively. At

-1.36 p(CO2) = 10 and pH = 7, when azurite is stable in all cases, total dissolved copper concentrations for the two E26 and the E22 ground water analyses are 3.26 x 10-6,

3.29 x 10-6 and 2.86 x 10-6, respectively. There is little evidence for increased total copper in solution as a result of elevated Cl-(aq) activities associated with E26. More copper is in solution associated with malachite at lower pH values (E22), as

29 Table 2.4.1. Calculated total dissolved copper loads (mol dm-3) for the aqueous solutions of Table 2.3.2, calculated at pH values of 5 to 7 and varying p(CO2) (see text). The calculations assume equilibrium conditions with respect to malachite, azurite or atacamite in line with stabilities indicated by Figure 2.3.6. ______[Cu]tot______p(CO2) pH E26P118 E26P119 E22P157 10-3.5 5 3.66x10-3 3.74x10-3 4.07x10-2 10-3.5 6 1.16x10-4 1.18x10-4 4.07x10-4 10-3.5 7 3.75x10-6 3.83x10-6 4.28x10-6 10-2.5 5 3.66x10-3 3.74x10-3 1.35x10-2 10-2.5 6 1.17x10-4 1.19x10-4 1.35x10-4 10-2.5 7 3.60x10-6 3.74x10-6 2.04x10-6 10-1.36 5 3.69x10-3 3.76x10-3 3.51x10-3 10-1.36 6 7.59x10-5 7.89x10-5 4.05x10-5 10-1.36 7 3.29x10-6 3.33x10-6 2.89x10-6

expected, and greater dispersion will have taken place under conditions where lower

Cl- activities prevailed and atacamite could not form. This result seems counter- intuitive at first in that CuCl+(aq) is expected to contribute to copper mobility, but it simply reflects solubility relationships for the carbonate minerals; acid reacts with carbonate and significant amounts of malachite and azurite can only form at higher pH values.

It is concluded that significant amounts of copper were dispersed from all three deposits during the acidic weathering event associated with secondary copper phosphate formation. In E22 (and presumably in E27), copper dispersion was greater than in E26 until approximately neutral pH was attained. Subsequently, there has been negligible difference in the relative extent of copper mobilisation from the three deposits. Taken together, these facts indicate that the total solution load of copper associated with weathering Northparkes-style mineralisation is largely independent of ground water salinity. Furthermore, the significant amounts of copper mobilised during the acidic weathering event, and those associated with later development of malachite-azurite-atacamite zones (particularly at lower pH values) is expected to generate a rather diffuse geochemical signature for the element, and one that would

30 have a considerable lateral extent. It is noted that Tonui et al. (2002) reported highly anomalous copper values in saprolite immediately adjacent to and overlying mineralisation in the E22 and E27 deposits. The results of the present work indicate that Northparkes style mineralisation should be detectable using geochemical exploration methods at some distance, in view of the reconstruction of the chemical conditions responsible for the development of supergene copper mineralisation in the regolith above E22, E26 and E27 deposits. This may have use in exploration strategies adopted in the region, especially with respect to blind mineralisation that has some weathering. The careful work of Tonui et al. (2002) with respect to appropriate sampling media in this setting should also be taken into account. Their conclusion that saprock is the preferred sampling medium at Northparkes is well- founded in the light of extensive leaching of copper in the upper oxidised zones.

31 Chapter 3

THE GEOCHEMISTRY OF FORMATION OF

LAVENDULAN

3.1 BACKGROUND

The mineral lavendulan was originally described by Breithaupt (1837) as a hydrous arsenate contaminated by nickel and copper from the Galliläische

Wirtschaft mine, Annaberg, . It was subsequently found at Jáchymov,

Czech Republic by Vogl (1853) and San Juan, Chile (Goldsmith, 1877). Uncertainty about its identity crept into the literature when Foshag (1924b) published findings that showed the material from Jáchymov was optically different to that from Chile.

The Chilean material gave a chemical formula of Na3(Cu,Ca)3(AsO4)2(OH)3·H2O, leading Foshag to rename it freirinite (Foshag, 1924a). However, powder X-ray studies by Guillemin (1956) showed that lavendulan and frerinite from both

Jáchymov and San Juan gave identical diffraction patterns. Analysis of the mineral from Chile and synthetic material gave the formula Na(Cu,Ca)6(AsO4)4Cl·4-5H2O

(or NaCaCu5(AsO4)4Cl·5H2O, its true composition). The mineral was shown to be isostructural with sampleite, NaCaCu5(PO4)4Cl·5H2O.

The ‘type’ specimen has recently been analysed and described as an amorphous mixture containing As and Zn with minor Cu, Co and S (Ondruš et al.,

2006). Thus the ‘type’ specimen bears no resemblance to established lavendulan.

Odruš et al. (2006) described the new mineral as a tetragonal dimorph of pseudo-tetragonal lavendulan, and the Ca analogue of zdenekite,

32 NaPbCu5(AsO4)4Cl·5H2O (Chiappero and Sarp, 1995). In describing lemanskiite they noted that some specimens thought to be lavendulan were in fact lemanskiite.

This included specimens of minerals from Talmessi in Iran, San Juan in Chile and

Postrama Murcia in . Powder X-ray measurements of material form Jáchymov and Laurion in confirmed the presence of lavendulan, although lavendulan from Laurion (Figure 3.2.1) transformed to lemanskiite several days after grinding.

However, Geister et al. (2007) suggested that lemanskiite may be a partly dehydrated and tetragonal or nearly tetragonal analogue of lavendulan and unequivocally established the isomorphous structural relationship between lavendulan and sampleite.

Figure 3.2.1. Lavendulan from Laurion, Greece. Field of view 660 m.

33 In order to adequately understand the mode of formation of lavendulan in relation to sampleite and other copper(II) arsenate minerals, its stability constant was determined at 298.2 K. This is described below, together with the chemical conditions that give rise to it and its congeners.

3.2 EXPERIMENTAL

3.2.1 Powder X-ray diffraction (XRD)

Powder X-ray diffraction (XRD) was commonly used for identification of minerals and synthetic phases. Measurements were carried out using a Philips

PW1925-20 powder diffractometer operating at 40 kV and 30 A using Ni-filtered

Cu Kα radiation ( = 1.5405 Å). Pure Si was used as internal standard when unit cell parameters were to be determined. Detected X-rays were recorded between 5 and 75°

2θ, with a step size of 0.02° and a rate of 1.2° per minute. Identification of phases present in diffraction patterns was effected using Diffraction Technology Data

Processing Software (Traces Version 6) with JCPDS-ICCD database files.

3.2.2 Total reflectance X-ray fluorescence (TRXRF) spectrometry

When no image capture was necessary, complementary, but qualitative, elemental analysis was carried out using a total internal reflectance XRF instrument of in-house design. The instrument is mounted on a Philips PW1729 generator operating at 40 kV and 35 mA to produce Mo Kα radiation ( = 0.7107 Å). A small amount of sample was placed on an optically flat quartz sample support and X-rays were detected with an Amptek XR-100CR Peltier-cooled X-ray detector. Energy profiles were created and analysed using Moran Scientific software.

34 3.2.3 Scanning electron microscopy (SEM)

Scanning electron microscopy was carried out using a JEOL 840

Microanalyzer, fitted with a thin window energy dispersive detector, controlled by

Moran Scientific acquisition and processing software. Energy dispersive spectrometry (EDS) was used for qualitative/semi-quantitative elemental analysis.

The system was operated at an accelerating voltage of 15 keV and a beam current of

20 nA. SEM was also employed for high magnification secondary electron (SE) image capture. Samples were coated with carbon prior to analysis to prevent charging.

3.2.4 Electron microprobe analysis

Quantitative elemental analysis was carried out using a JEOL JXA 8600

Superprobe equipped with three wavelength dispersive spectrometers, analysing from Be to U, and a Kevex energy dispersive spectrometer analysing from Na to U controlled by Moran Scientific software. Samples were embedded in epoxy resin, ground flat and polished with 1 m and 0.25 m diamond pastes before being carbon coated. Samples were analysed at an accelerating voltage of 15 keV and a beam current of 20 nA. Standards used for each element and minimum detection limits are given in Table 3.2.1.

3.2.5 Atomic absorption spectroscopy (AAS)

AAS measurements (Cu) were carried out with a Perkin Elmer AAnalyst 100

-3 instrument using matched standards. Standards of CuCl2·2H2O in 0.1 mol dm NaCl were prepared using pre-calibrated glassware. Measurements of pH were taken using a Radiometer PHM 93 meter fitted with an IJ44 combination electrode.

35 Table 3.2.1 Element standards and minimum detection limits (MDL) for electron microprobe analyses. Element Standard MDL (wt%) Na Jadeite 0.019 K Orthoclase 0.013 Ca Fluorite 0.019 Pb sulfide 0.123 Cu Cu metal 0.022 P 0.028 As Gallium arsenide 0.048 Cl Thallium chloride 0.017 Cd Cadmium metal 0.228 Ni Ni metal 0.153 Zn Zn metal 0.239 Mg 0.021

3.2.6 Lavendulan synthesis

Pure lavendulan was synthesised as follows. CaCl2 (0.1110 g, 1 mmol),

CuCl2·2H2O (0.8520 g, 5 mmol), Na2HAsO4 (1.2487 g, 4 mmol) and NaCl (5.843 g,

0.1 mol) were added to a Teflon-lined Parr acid digestion bomb together with 75 cm3 of deionised water. The bomb was heated to 100oC for 48 hours and then cooled slowly to room temperature. The product was collected at the pump, washed with water, then acetone, and sucked dry. Use of lesser amounts of NaCl resulted in mixtures of lavendulan and . Gram quantities of lavendulan were easily obtained using the above procedure. No phases other than lavendulan were detected in the product using XRD and satisfactory analyses corresponding to the stoichiometric formula were obtained.

3.2.7 Solution studies

Preliminary studies showed that lavendulan dissolves incongruently in aqueous 10-3 mol dm-3 HCl solution to give mixtures of lavendulan and olivenite.

However, the mineral does dissolve congruently in aqueous 10-3 mol dm-3 HCl

36 solution that is also 0.1 mol dm-3 in NaCl. Excess solid lavendulan was equilibrated in several sealed flasks with 100 cm3 of aqueous 10-3 mol dm-3 HCl and 0.1 mol dm-3

NaCl. The flasks were placed in a shaking water bath and maintained at 25 ±0.1oC.

Parallel experiments were conducted to monitor pH changes as the solutions reached equilibrium with lavendulan. No pH change was observed after two weeks, but solutions were kept in the water bath for a further six weeks. At this time, the pH of each equilibrated solution was recorded and the sample filtered through a 0.7 m fibreglass disc. Measurement of total dissolved Cu was carried out using AAS. For the seven experimental runs undertaken, total dissolved Cu concentrations (x 10-4 mol dm-3) with equilibrium pH values in parentheses were 5.635 (4.511), 5.537

(4.522), 5.635 (4.523), 5.870 (4.525), 5.870 (4.528), 5.503 (4.526) and 5.503 (4.530).

This leads to a solubility of lavendulan, NaCaCu5(AsO4)4Cl·5H2O, of 1.24 ±0.03 x

10-4 mol dm-3 at 298.2 ±0.1 K and a pH of 4.524 ±0.006.

In order to calculate a stability constant for lavendulan, species distribution calculations using the solubility of the mineral were carried out for each of the experimental runs. Species incorporated in the COMICS calculations (Perrin and

Sayce, 1967) are shown in Table 3.2.1.

Table 3.2.1 Equilibrium constants for complex species when I = 0.1 used in determining species distributions. Species Log K CuOH+ -8.02 CaOH+ -13.02 2- HAsO4 11.95 - H2AsO4 17.60 0 H3AsO4 19.74 0 CaHAsO4 13.94 + CaH2AsO4 18.78 CuCl+ -0.03 0 CuHAsO4 15.38 + CuH2AsO4 19.12

37 Stability constants (Martell and Smith, 1982; Smith and Martell, 1976, 1989) were corrected to an ionic strength of I = 0.102 mol dm-3 using the Davies modification of the Debye-Hückel equation, taking γ for neutral species to be equal

2 ½ ½ to unity, at 298.2 K (lgγi = -0.5085zi [I /(1 + I ) –0.3I], where zi is the charge on species i). Calculated equilibrium concentrations of the free aquated ionic species

+ 2+ 2+ - - -4 -4 Na , Ca , Cu , H2AsO4 and Cl were 0.1001, 1.217 x 10 , 5.160 x 10 ,

3.980 x 10-4 and 0.1011 mol dm-3, respectively, for the average solubility of lavendulan at pH 4.524 (for all data, see Table A.1 in the Appendix). These values, together with lgγ± = -0.108, lgγ2± = -0.430 and lgγ3± = -0.968 (I = 0.102 mol dm-3) were used in turn to calculate KH, with respect to equations 3.1 and 3.2 below, where a(i) is the activity of species i (a(i) = m(i)γ(i), with m(i) being the concentration of species i).

+ + 2+ 2+ NaCaCu5(AsO4)4Cl·5H2O(s) + 8H (aq) ⇋ Na (aq) + Ca (aq) + 5Cu (aq) +

- - 4H2AsO4 (aq) + Cl (aq) + 5H2O(l) (3.1)

+ 2+ 2+ 5 - 4 - + 8 KH = a(Na )a(Ca )a(Cu ) a(H2AsO4 ) a(Cl )/a(H ) (3.2)

At 298.2 K, log KH is equal to -2.54 ±0.08. From this result, the standard free energy

o of formation of lavendulan is ΔfG (NaCaCu5(AsO4)4Cl·5H2O,s,298.2 K) = -4839.1

±6.2 kJ mol-1. With respect to this quantity, values for the free energies of formation of component ions and water were taken from Robie and Hemingway (1995), except

- - -1 for H2AsO4 (aq). The value used for H2AsO4 (aq) at 298.2 K (-753.9 ±0.12 kJ mol )

3- was derived from a value for the corresponding AsO4 ion together with the first and second proton association constants given by Smith and Martell (1976)and Martell

38 and Smith (1982). The total error in ΔfGo for lavendulan was calculated by the addition of the errors for individual species (Robie and Hemingway, 1995) and the

o 2+ calculated error in log KH. It is noted that no errors are listed for ΔfG for Ca (aq)

- -1 and H2AsO4 (aq); these are estimated to be 0.1 and 0.12 kJ mol , respectively.

3.3 GEOCHEMISTRY OF MINERAL FORMATION

3.3.1 Phase relationships

The chemistry of formation of a number of copper(II) , carbonates and chlorides have been described in the literature, but for a large number of arsenate species reliable thermodynamic properties are yet to be determined. For geochemical modelling purposes, thermodynamic properties (stability constants) of common

Cu(II) arsenate minerals are available and these, together with the presently determined value for lavendulan have been used to construct relevant phase diagrams. Stability field diagrams show the chemical conditions under which the various minerals crystallise from aqueous solutions and can explain observed paragenetic sequences. Thermodynamic data for associated arsenate minerals have been listed in Table 3.3.1, along with similar data for relevant dissolved species. It should be noted here that errors in values of ΔfGº (298.2 K), derived from uncertainties for component dissolved species, cancel out in calculations describing the equilibrium conditions between a pair of stable minerals.

A stability field diagram for lavendulan and associated copper(II) arsenate minerals is shown in Figure 3.3.1. Using the thermodynamic data from Table 3.3.1, boundaries for mineral pairs were calculated for aCa2+ = 10-5, the predominant

- arsenate species being H2AsO4 when pH is between 2.1 and 7.0. The diagram shows the change in the lavendulan stability field when the chloride activity is increased

39 Table 3.3.1. ΔfGº (298.2 K) for minerals and dissolved species used in geochemical modelling calculations. Species Formula ΔfGº (kJ mol-1) Referencea

Atacamite Cu2Cl(OH)3 -667.55 1 Lammerite Cu3(AsO4)2 -1300.8 1 Olivenite Cu2AsO4(OH) -846.4 ± 1.6 1 Cu5(AsO4)2(OH)4 -2057.9 ± 4.1 1 Cu3AsO4(OH)3 -1211.2 ± 2.7 1 Conichalcite CaCuAsO4(OH) -1471.7 ± 3.3 1 Lavendulan NaCaCu5(AsO4)4Cl·5H2O -4839.1 ± 6.2 2 Cu2+ +65.1 ± 0.1 3 Ca 2+ -553.6 3 Na+ -261.5 3 Cl- -131.2 3 - H2AsO4 -753.89 4 a[1] Williams (1990); [2] this study; [3] Robie and Hemingway (1995); [4] Martell and Smith (1982); Smith and Martell (1976, 1989).

234567pH 0

Cornwallite

-2 Olivenite Clinoclase

Lammerite ) 2+

-4 (Cu a lg

Lavendulan Conichalcite -6

a (Cl-) 10-3 10-2 2+ -5 10-1 a (Ca ) = 10 -8

Figure 3.3.1. Stability fields for lavendulan and selected Cu(II) arsenates relative to 2+ 2+ -5 - -3 aCu and pH, when aCa = 10 . Boundaries are drawn for aCl = 10 (solid lines), - -2 - -1 aCl = 10 (dotted lines) and aCl = 10 (dashed lines).

40 from 10-3, corresponding to weakly saline groundwater, to 10-1, corresponding to strongly saline groundwater (Williams, 1990). It is not unreasonable to consider chloride activities of these magnitudes as very saline grounds waters can be present in oxidising sulphide ores. In fact, a large number of chloride minerals including lavendulan are a feature of oxide zones located in arid and semi-arid areas (see below), or alternatively associated with saline groundwaters such as was the case with sampleite at Northparkes, as discussed previously.

The rarity of lavendulan compared with the more common copper(II) arsenates can be readily explained with reference to Figure 3.3.1. When the activity of chloride is high and the pH is low, lavendulan is stable over a wide range of copper activities. As activity of chloride increases from weakly saline to strongly saline conditions, the stability field of lammerite is impinged upon by that of lavendulan until it is completely eliminated at a chloride activity of 10-1. At localities such as the south pit of the Gold Hill mine, Utah, lavendulan is found in association with other Cu(II) arsenates including olivenite, cornwallite and conichalcite

(Kokinos and Wise, 1993). While lavendulan requires a low pH regime to form, its association with these minerals (particularly cornwallite) indicates a wide range of pH values associated with the complete assemblage. Elsewhere in the same deposit clinoclase is also known to form, indicating yet higher pH values were ultimately achieved.

The activity of calcium in the mineralising system greatly affects the stability of lavendulan and the other Cu(II) arsenates. Figure 3.3.2 is a stability field diagram for the copper(II) arsenates constructed in the same fashion as Figure 3.3.1, but with an increased activity of Ca2+ of 10-3. This results in conichalcite significantly encroaching on the stability field of lavendulan, and also those of olivenite,

41 234567pH 0

Olivenite Cornwallite

Lammerite Clinoclase -2 Lavendulan ) 2+

-4 (Cu a

lg Conichalcite

-6 10-3

10-2 a (Cl-) 10-1 a (Ca2+) = 10-3 -8

Figure 3.3.2. Stability fields for lavendulan and selected Cu(II) arsenates relative to 2+ 2+ -3 - -3 aCu and pH, when aCa = 10 . Boundaries are drawn for aCl = 10 (solid lines), - -2 - -1 aCl = 10 (dotted lines) and aCl = 10 (dashed lines).

cornwallite and clinoclase. As calcium is readily available in groundwaters associated with oxidising orebodies, it is therefore not unexpected that conichalcite is much more common than lavendulan in copper arsenate assemblages.

As predicted by the above stability field diagrams, olivenite and conichalcite are close associates of lavendulan in many deposits (Anthony et al., 2003). The association of lavendulan, olivenite and conichalcite may be seen as being the result of subtle fluctuations in the activities of Cl-, Ca2+ and Cu2+. An example of this is reflected by the supergene mineralisation of the Dome Rock deposit, South Australia, from which occurrences of lavendulan, conichalcite, olivenite and other arsenate minerals have been reported (Kleeman and Milnes, 1973; Ryall and Segnit, 1976;

42 Segnit, 1976). Pseudomorphs of conichalcite after olivenite are found, indicating that conichalcite is later in the paragenetic sequence (Ryall and Segnit, 1976). Olivenite is rare in the deposit, with some pseudomorphs of conichalcite after olivenite still retaining an olivenite core (Segnit, 1978). With reference to Figures 3.3.1 and 3.3.2 this may be considered the result of increasing activity of calcium ions, or increasing activity of copper ions, with constant pH. The low pH necessary for lavendulan formation is also confirmed by the presence of the mineral , FeAsO4·2H2O, from this deposit (Segnit, 1976). Scorodite can only be formed at pH values less than those which serve to stabilise goethite, FeOOH.

Lavendulan has been observed in a number of deposits associated with scorodite or its aluminium analogue , AlAsO4·2H2O. These minerals are indicative of very acidic conditions of formation; to form scorodite a pH of less than

2 is required (Zhu and Merkel, 2001). XRD analysis of material from the El Guanaco mine, Taltal, Chile, showed lavendulan to be associated with mansfieldite (Figure

3.3.3). The occurrence of dark blue green crystals of lammerite associated with the lavendulan from the same deposit (Geister et al., 2007) is also indicative of low pH conditions (vide supra).

Figure 3.3.4 is a stability field diagram showing relationships between selected Cu(II) arsenates and atacamite at 298.2 K. Atacamite is used as a proxy for all Cu(II) chloride minerals with a Cu2Cl(OH)3 stoichiometry. The diagram clearly shows that high arsenate activities and relatively low pH values are necessary for lavendulan to crystallise from mineralising solutions. In addition, the combination of very low pH and very high copper and arsenate activities required for the formation of lammerite goes some way to explaining its rarity. The formation of the arsenates cornwallite and clinoclase is precluded by atacamite and conichalcite at the

43

Figure 3.3.3. Lavendulan associated with minor mansfieldite from El Guanaco, Taltal, Chile. Field of view is 5cm.

23456789pH 0 Lavendulan

-2 Lammerite ) -

4 -4 Conichalcite

Olivenite AsO 2 (H a -6 lg

-8 a (Cl-) -2 Atacamite 10 10-1 100 -10 Figure 3.3.4. Stability fields for lavendulan and selected Cu(II) arsenates relative to - 2+ -5 - 0 a(H2AsO4 ) and pH, when aCa = 10 . Boundaries are drawn for aCl = 10 (solid - -1 - -2 lines), aCl = 10 (dotted lines) and aCl = 10 (dashed lines).

44 levels of calcium and chloride on the diagram. The association of lavendulan with olivenite, Ni-rich paratacamite (an isomorph of atacamite) and gillardite

(Cu3NiCl2(OH)6; see following Chapter) in the Widgiemooltha 132N deposit (Nickel et al., 1994) is indicative of the variations in the activities of arsenate and chloride in the oxidised zone that are necessary to develop the assemblage.

It is possible to compare relationships between the analogous phosphates of the species considered above. Although not as common as their arsenate analogues, sampleite and the Cu(II) phosphates have been identified from numerous locations including Northparkes, N.S.W., as discussed in Chapter 2. Mineralising solutions in the supergene zone are generally more likely to be rich in arsenate rather than phosphate. This is the result of the oxidation of common primary assemblages that contain arsenopyrite, FeAsS, löllingite, FeAs2, or other As-bearing sulfosalts, which are frequently associated with complex base metal deposits. Phosphate, on the other hand, needs to be mobilised from minerals such as apatite, which may be somewhat remote from the oxidising sulfide body (Williams, 1990). Figure 3.3.5 is a stability field diagram showing relationships between atacamite, sampleite and other Cu(II) phosphates at 298.2 K. The diagram was constructed using a value for a(Na+) equal to that of the chloride ion, and 10 times that of the calcium ion. Sampleite, like lavendulan, occupies an area of the stability field diagram requiring elevated chloride activities. As was the case for the arsenates lammerite and olivenite, the stability fields of libethenite and pseudomalachite are eliminated as the activity of chloride increases. An obvious difference is the absence of a phosphate analogue of conichalcite, which is unknown naturally or as a synthetic phase. As such, the

45 23456789pH 0

Sampleite -2

Libethenite a (Cl-)=10-2 ) - -4 -1 4 a (Cl-)=10 PO 2 a (Cl-)=100 (H a -6 Pseudomalachite lg

Cornetite

-8

Atacamite

-10

Figure 3.3.5. Stability fields for sampleite and selected Cu(II) phosphates and - - 0 chlorides relative to a(H2PO4 ) and pH. Boundaries are drawn for aCl = 10 (solid - -1 - -2 lines), aCl = 10 (dotted lines) and aCl = 10 (dashed lines).

stability field of sampleite is not restricted in the same way as lavendulan by rising calcium activities. In fact, an increase in the activity of calcium serves to make the stability field for sampleite even larger.

At present, sampleite is known from 16 localities and lavendulan from 103

(www.mindat.org). This simply reflects the relative availability of arsenate and its protonated species from a wider range of primary deposits. Lower pH regimes are inevitably associated with oxidising As-rich primary phases. A simple examination of the mass balances involved with the oxidation of pyrite versus arsenopyrite bears

46 this out. Equations 3.3 to 3.5 describe the oxidation of these two phases with goethite acting as a repository for Fe(III).

2+ 2- + FeS2 + 7/2O2 + H2O → Fe + 2SO4 + 2H (3.3)

2+ 2- 3- + FeAsS + 13/4O2 + 3/2H2O → Fe + SO4 + AsO4 + 3H (3.4)

2+ + Fe + 1/4O2 + 3/2H2O → FeOOH + 2H (3.5)

The oxidation of one mol of pyrite and one mol of arsenopyrite give four and five mol of protons, respectively. In effect, if saline (chloride) groundwaters are associated with an oxidising Cu- and As-rich primary deposit, the conditions likely to give rise to lavendulan are in a sense inevitable.

3.4 SOLID SOLUTION PHENOMENA INVOLVING

LAVENDULAN AND RELATED MINERALS

Giester et al. (2007) proposed a reclassification of the lavendulan group, to include zdenekite, lemanskiite, mahnerite and shubnikovite, as well as richelsdorfite, bleasdaleite, andyrobertsite, calico-andyrobertsite(-1M) and calico-anydyrobertsite(-

2O). Little information is available in the scientific literature about solid solution and extent of substitution between members of the lavendulan group. It would be reasonable to expect that lavendulan and sampleite would exhibit solid solution at

3- 3- least to some extent, particularly as the PO4 and the AsO4 ions have the same charge and shape, about the same radius (238 and 248 pm, respectively) and practically the same conjugate acid pKa values at 298.2 K, as shown in equations 3.6 to 3.8 below, ignoring state terms (Martell and Smith, 1982).

47 - + H3XO4 ⇋ H2XO4 + H pKa = 2.148 (P), 2.24 (As) (3.6)

- 2- + H2XO4 ⇋ HXO4 + H pKa = 7.199 (P), 6.96 (As) (3.7)

2- 3- + HXO4 ⇋ XO4 + H pKa = 12.35 (P), 11.50 (As) (3.8)

The isomorphous minerals lavendulan, sampleite and zdenekite crystallise in space group P21/n (Giester et al., 2007; Zubkova et al., 2003). On the basis of the close chemical similarities above, it is likely that solid solution involving arsenate and phosphate in lavendulan and sampleite would display close to ideal behaviour.

This is supported by the close match of their stability constants. Theoretical considerations for this have been outlined by Williams (1990). An equation (3.9) can be written for phosphate-arsenate substitution as shown below.

- - NaCaCu5(AsO4)Cl·5H2O(s) + 4H2PO4 ⇋ NaCaCu5(PO4)Cl·5H2O + 4H2AsO4 (3.9)

The calculated value of ΔrG°(298.2K) for this reaction is 3.2 kJ mol-1, a rather low number with respect to the cited free energy of formation data for the species, and corresponds to an equilibrium constant of 0.27. Thus, phosphate or arsenate may substitute in the appropriate lattice more or less freely depending on their availability in mineralising solutions. A larger equilibrium constant would be necessary to limit arsenate-phosphate anion substitution in the sampleite-lavendulan pair (Williams, 1990).

Solid solution between the end members is indeed known from several localities. Lavendulan with 21 mol% substitution of phosphate for arsenate was reported from the Dome Rock mine, South Australia (Kleeman and Milnes, 1973).

Microprobe analyses of lavendulan from several other localities are shown in Table

3.4.1.

48 Table 3.4.1 Microprobe analyses (wt%) of lavendulan by locality. Chemistry Ideal Dome Rocka San Juanb Widgiemoolthac Na2O 2.92 3.3 3.1 2.84 CaO 5.28 5.7 5.8 4.84 CuO 37.45 38.2 36.3 37.46 CoO 0.03 As2O5 43.28 36.4 44.8 42.2 P2O5 6.0 2.39 Cl 3.34 5.5 3.5 3.26 H2O 8.48 6.0 7.3 7.74 -O = Cl 0.75 1.2 0.8 0.73 aKleeman and Milnes (1973), bAnthony et al. (2003), cthis work, average of 6 analyses, with H2O calculated by difference.

Analyses of Broken Hill sampleite (pictured in Figure 3.4.1) show that lead substitution for calcium can also occur (Birch, 1999), suggesting possible solid solution between sampleite and zdenekite. At the other end of the spectrum, sky-blue spherules of zdenekite, closely resembling lavendulan, have been reported by Birch

(1990) from Block 14 with up to 20 mol% calcium replacing lead (Birch, 1999).

Calcium replacing lead in zdenekite from the Cap Garonne mine, (the type locality) with a ratio of Pb:Ca = 88:12 has been reported, with a possible restricted solid solution between lavendulan and zdenekite put forward by Chiappero and

Figure 3.4.1. Sampleite associated with , and libethenite from Block 14 open-cut, Broken Hill, N.S.W. Field of view is 4mm.

49 Sarp (1995). However, it is not possible to comment in the same way on Pb-Ca substitution, in the absence of stability constant data for zdenekite. It is noted in passing that successful attempts have been made to synthesise zdenekite using the same methods as employed for sampleite and lavendulan, but substituting PbCl2 for

CaCl2. However, the zdenekite obtained was always contaminated by ,

Pb5(AsO4)3Cl. The yield of mimetite could be reduced by increasing the amounts of

NaCl used in the synthesis, but it was never eliminated, even under conditions of halite saturation. Zdenekite must then form at very high activities of chloride, and perhaps at lower arsenate activities. Its association with mimetite at Broken Hill is noted (Birch, 1999).

The lavendulan in the Widgiemooltha 132 N deposit, Western Australia occurs with a wide range of secondary nickel minerals (Nickel et al., 1994). Electron microprobe analyses of lavendulan from this deposit in the present study indicate substitution of phosphate for arsenate at levels of between 4 and 10 mol%. Although substitution of Ni2+ in the lavendulan lattice might be expected given the high activity of nickel in the mineralising system at the 132 N deposit, analyses show no substitution for copper. An examination of the of lavendulan

(Giester et al., 2007) reveals that all Cu atoms in the lattice are 5-coordinate in Jahn-

Teller distorted sites. This coordination geometry is evidently unsuited to the requirements of the Ni(II) ion. Nickel does, however, substitute for copper in other copper minerals of the deposit, including paratacamite. Nickel et al. (1994) reported nickeloan paratacamite from Widgiemooltha 132 N containing up to 17.4 mol% Ni.

During this study, electron microprobe analyses of material from this locality, together with a single crystal X-ray structure, reveal a Cu:Ni ratio of 3:1 (Clissold et al., 2007). The Cu site is strongly Jahn-Teller distorted, and the Ni site is regular

50 with respect to Ni-O bond lengths but with a slight angular distortion. The resulting new mineral, gillardite, Cu3NiCl2(OH)6, is discussed in detail in Chapter 4.

Nickel-rich magnesite and dolomite are conspicuous in the upper section of the carbonate zone at Widgiemooltha 132N (Nickel et al., 1994). Figure 3.4.2 shows gillardite associated with gaspéite, NiCO3, and gypsum. The behaviour of members of the gaspéite-magnesite solid solution series in the supergene zone can be described effectively using a very simple equilibrium thermodynamic approach

(Clissold et al., 2003). This is possible because of the similarity between the radii of the Ni(II) and Mg(II) ions and their compatibility with regular octahedral coordination sites. It should be noted that there is no smooth transition between regions of different composition in samples from the 132 deposit. Rather, a number of abrupt phase changes are observed (Figure 3.4.3). Electron microprobe analyses show that the bright core in Figure 3.4.3 is gaspéite, the light edge dolomite, the dark edge magnesite and the thin bright line gaspéite. In particular, Ni-rich areas are most pronounced when they are embedded in material carrying more Mg. The deposition sequence observed is Ni-rich > Ca- and Mg-rich → Mg-rich → Ni-rich → Mg-rich.

Values of lgKsp at 298.2 K are -7.505, -8.25 and -8.35 for gaspéite, magnesite and calcite, respectively (Robie and Hemingway, 1995; Wallner et al., 2002). The simple thermodynamic model that can be used to describe the compositions of the carbonates analysed rests upon a consideration of the relative solubility products of the solid carbonate phases and their interconversions. In this connection the solid solution is assumed to behave ideally.

First for the magnesite-gaspéite pair, the following may be derived using recently determined thermodynamic data at 298.2 K (Wallner et al., 2002). For the reaction below (3.10), lgK is equal to -0.75.

51

Figure 3.4.2. Gillardite associated with gaspéite and gypsum from Widgiemooltha 132 N deposit. Field of view is 4mm.

Figure 3.4.3. Backscattered electron image of gaspéite, dolomite and magnesite (right to left) Widgiemooltha 132 N deposit. Field of view is 350 m.

52

2+ 2+ MgCO3(s) + Ni (aq) ⇋ NiCO3(s) + Mg (aq) (3.10)

This implies that for equal substitution into the lattice, the activity of Ni2+ ion only needs to be about 5 times greater than that of the Mg2+ ion. In other words, given a geochemical setting in which magnesite can form, any available Ni2+ will be easily incorporated into the magnesite lattice. Other relevant equilibrium data are tabulated in Table 3.4.2.

Table 3.4.2. LgKSP values for carbonate minerals used in calculations of relative stabilities of species at I = 0 (298.2K) a Species Formula LgKsp Reference 2+ 2- Gaspéite NiCO3(s) ⇋ Ni (aq) + CO3 (aq) -7.505 1, 2 2+ 2- Magnesite MgCO3(s) ⇋ Mg (aq) + CO3 (aq) -8.25 3 2+ 2- Calcite CaCO3(s) ⇋ Ca (aq) + CO3 (aq) -8.39 3 a[1] Martell and Smith (1982); Smith and Martell (1976, 1989);[2] Wallner et al. (2002); [3] Robie and Hemingway (1995).

Similar conclusions are reached for the substitution of Ni in calcite. For reaction 3.11;

2+ 2+ CaCO3(s) + Ni (aq) ⇋ NiCO3(s) + Ca (aq) (3.11)

log K is equal to -0.89 and the corresponding ratio of Ca2+/ Ni2+ activities amounts to approximately 0.14. The salient geochemical conclusion that may be drawn is that Ni is preferentially and selectively immobilised in the carbonate suite under equilibrium conditions.

53 Chapter 4

GILLARDITE, Cu3NiCl2(OH)6, A NEW MINERAL FROM

THE 132 NORTH DEPOSIT, WIDGIEMOOLTHA,

WESTERN AUSTRALIA

4.1 HISTORY

The 132 North deposit, is situated 5 km north-northwest of the hamlet of

Widgiemooltha, Western Australia (31° 30' S, 121° 34' E), about 80 km south of the city of Kalgoorlie (Figure 4.1.1). An open cut exposed an extensive oxidised zone developed on a -hosted sulfide deposit. The main sulfide minerals present were pyrrhotite, , pyrite and chalcopyrite (Marston et al., 1981; McQueen,

1981). A remarkable array of secondary Ni and Cu minerals was found in the oxidised zone and these have been thoroughly documented by Nickel et al. (1994).

Among these, specimens of “nickeloan paratacamite”, with compositions reaching

Cu3NiCl2(OH)6, were noted. In light of the report of the new species herbertsmithite,

Cu3ZnCl2(OH)6 (Braithwaite et al., 2004), it seemed likely that this material was also a new species. This has proved so and the material is described below as gillardite.

The new mineral and its name were approved by the Commission on New Minerals and Mineral Names, IMA (IMA 2006-041). The holotype is housed in the Gartrell

Collection, specimen number 8774, of the Department of Earth and Planetary

Sciences, Western Australian Museum, Perth, WA. The mineral is named in honour of Professor Robert David Gillard (1936-), formerly of the Department of Chemistry,

Cardiff University, Wales, UK, in recognition of his contributions to inorganic chemistry, especially in the field of coordination chemistry.

54

Figure 4.1.1. Location of the Widgiemooltha 132 N deposit.

4.2 OCCURRENCE

Aggregates of equant, rhombohedral crystals up to 0.5 mm in size in a silicified ferruginous gossan were examined. Clusters of dark green gillardite and smaller, paler bottle-green clinoatacamite crystals are scattered across the ferruginous gossan matrix (Figure 4.2.1). Nickel et al. (1994) reported “nickeloan paratacamite” crystals up to several mm in size from throughout the carbonate zone of the oxidised profile. Associated secondary minerals in the deposit are gaspéite, gypsum, magnesite, carrboydite, motukoreaite, glaukosphaerite, hydrohonessite, retgersite, pyrolusite, huntite, aragonite, pecoraite, dolomite, kambaldaite,

55

Figure 4.2.1. Section of the holotype specimen of gillardite. Individual crystals range up to 0.3 mm in size.

, azurite, lavendulan, nepouite, nullaginite, olivenite, otwayite, pharmacosiderite, reevesite, takovite, widgiemoolthaite and kambaldaite in a silicified ferruginous gossan (Nickel et al., 1994).

4.3 CHEMICAL COMPOSITION

A crystal cluster of gillardite was embedded in epoxy resin, polished and carbon-coated. Twelve spot analyses were carried out using a Jeol JXA 8600 electron microprobe operating with an accelerating voltage of 20 keV, beam current of 20 nA, and with a 3 m beam diameter. No Zn was detected in any analysis. The sample used for microprobe analysis was somewhat unstable in the beam. A single TGA analysis (TA Instruments SDT 2960) for H2O was performed. Analytical results are given in Table 4.3.1. No other elements than those reported were detected (Jeol JXA-

840 SEM equipped with a light element detector EDS system). The empirical

56 Table 4.3.1. Analytical data for gillardite. Constituent wt% Range Probe Standard CuO 55.6 54.2-58.6 Cu NiO 15.3 14.3-17.4 Ni CoO 0.2 <0.1-0.4 Co FeO 0.1 <0.1-0.3 FeS2 Cl 17.3 15.9-18.8 TlCl H2O 13.1 Less O=Cl -3.9 Total 97.7

formula (based on 2Cl pfu) is (Cu2.865Ni0.840Co0.011Fe0.006)Σ3.722Cl2(OH)5.960.

Normalisation of the metal distribution to 4 metal ions pfu gives

(Cu3.08Ni0.90Co0.01Fe0.01)Σ4.00Cl2(OH)5.96. Spot analyses show variation of Cu:Ni ratios and metal occupancies range from (Cu3.135Ni0.853Co0.012) to (Cu2.922Ni1.058Co0.020).

Other analyses are given in Nickel et al. (1994). The simplified formula is thus

Cu3.1Ni0.9Cl2(OH)6 or Cu3NiCl2(OH)6.

4.4 PHYSICAL AND OPTICAL PROPERTIES

Equant, rhombohedral crystals showing the forms {1011}, {02 2 1}, {0001} and {1010} (probable) are dark green in colour and larger crystals are nearly black

(Figure 4.4.1). No twinning was observed. Gillardite is non-fluorescent, has a green and is transparent with a vitreous . Mohs hardness is 3, fracture is splintery and uneven, and the tenacity is brittle. No parting was observed, but is good on {1011}. The calculated density is 3.76 g cm-3, from the single- crystal structure analysis. Gillardite is uniaxial (+), with ω = 1.836 ± 0.002, = 1.838

± 0.002 (white light). No dispersion or was observed. The Gladstone-

Dale compatibility index, calculated using the empirical formula

(Cu3.08Ni0.90Co0.01Fe0.01)Σ4.00Cl2(OH)5.96 and unit-cell parameters from the single-

57 crystal structure analysis is -0.032 (excellent). After dissolution of gillardite in 6M

HNO3, reaction with dimethylglyoxime (DMGH) and excess NH3 gives a heavy precipitate of Ni(DMGH-1)2. Reaction of the acidic solution with potassium mercuric thiocyanate gives pale yellow-green rosettes of copper mercuric thiocyanate crystals.

Addition of AgNO3 solution and adjustment of pH with ammonia gives a white precipitate of AgCl. The mineral decomposes with complete loss of water at 300oC.

Figure 4.4.1. Crystal drawing of gillardite.

4.5 SINGLE-CRYSTAL X-RAY STRUCTURE

Data collection was performed on a Bruker SMART CCD diffractometer at

273(2) K with graphite-monochromated Mo Kα radiation (λ = 0.71073 Å). Data were corrected for Lorentz, polarisation and absorption effects, the latter using

SADABS (Sheldrick, 1996). Maximum and minimum apparent transmission factors were 1.225 and 0.850, respectively. The structure was solved by direct methods

58 using SHELXS97 (Sheldrick, 1997a) and refined by least-squares procedures using

SHELXL97 (Sheldrick, 1997b). The locations of the metal (Cu and Ni) and atoms were found to be in similar positions to the analogous atoms in the R3m substructure of paratacamite reported by Fleet (1975). In line with the results of the electron-microprobe analyses, which indicate a Cu:Ni ratio of close to 3:1, the divalent copper fully occupies the MO4Cl2 site, whereas nickel occupies the non- tetragonally distorted MO6 site. This is also consistent with the metal ion distribution reported for herbertsmithite (Braithwaite et al., 2004), with which gillardite is isomorphous. A difference map then revealed the position of the hydroxyl atom, and in a similar position to that found for one of the two disordered oxygen atoms in the paratacamite substructure (Fleet, 1975). An isotropic refinement gave

R1 = 0.025 and a subsequent difference-map clearly revealed the atom position of the hydroxyl group, ca 0.83 Å from the oxygen atom. The hydroxyl group is probably oriented in a similar fashion in herbertsmithite, but as no atom coordinates were listed (Braithwaite et al., 2004) this can only be assumed. The complete structure then refined smoothly with anisotropic displacement parameters for the non-hydrogen atoms to an R1 of 0.011. A final refinement was performed using a mixed occupancy for the nickel atom position, in line with the analytical results, (Ni0.901Cu0.081Co0.012Fe0.004). This resulted in no significant change to the structure. Final R1 and wR2 values were 0.011 and 0.027, respectively, for 448

2 2 unique reflections with I > 2σ(I). The weighting scheme used was w = 1/(σ Fo +

2 2 2 0.081P +1.700P), where P = (Fo + 2Fc )/3, as defined by SHELXL97 (Sheldrick,

1997b). Crystal data and structure refinement details are given in Table 4.5.1. Final coordinates of the atoms are listed in Table 4.5.2, anisotropic displacement parameters in Table 4.5.3, and selected bond-lengths and angles in Table 4.5.4.

59

Table 4.5.1. Crystal data and structure refinement details for Cu3NiCl2(OH)6. Chemical formula Cu3.081Ni0.903Co0.012Fe0.004Cl2O6H6 Mr 422.66 Rhombohedral Space group R3 m Unit-cell dimensions (Å) a = 6.8364(1), c = 13.8459(4) V (Å3) 560.41(2) Z 3 Density (Calc.) (Mg m-3) 3.76 (Mo Kα) (mm-1) 11.6 F(000) 609.2 Crystal size (mm) 0.22 x 0.21 x 0.23 θ range for data collection (°) 3.74-40.33 Index ranges -11≤h≤12, -11≤k≤12, -24≤l≤22 Reflections measured 8443 Independent/observed reflections 454/448 (Rint = 0.022) Data/parameters 454/20 Goodness-of-fit on F2 1.062 Final R indices [I > 2.0σ(I)] R1 = 0.0112 (wR2 = 0.0274) Final R indices (all data) R1 = 0.0114 (wR2 = 0.0274) -3 Largest diff. peak/hole (e Å ) 0.63/-0.53

Table 4.5.2. Final atomic coordinates and equivalent isotropic displacement 2 parameters (Å ) for Cu3NiCl2(OH)6 (U(eq) is defined as one third of the trace of the orthogonalised Uij tensor). x/a y/b z/c U(eq) Ni(1) 0 0 ½ 0.0043(1) Cu(2) ½ 0 0 0.0054(1) Cl 0 0 0.1933(1) 0.0073(1) O 0.2070(1) -x 0.0624(1) 0.0073(12) H 0.1440(11) -x 0.0858(14) 0.022(6)

Table 4.5.3. Anisotropic displacement parameters (Å2) for the non-hydrogen atoms of Cu3NiCl2(OH)6 (the anisotropic displacement factor exponent takes the form - 2 2 2π [h a*2U11 + ... + 2hka*b*U12]) U11 U22 U33 U23 U13 U12 Ni(1) 0.0049(1) U11 0.0031(1) 0 0 0.5U11 Cu(2) 0.0053(1) 0.0049(1) 0.0058(1) 0.0011(1) 0.5U23 0.5U22 Cl 0.0080(1) U11 0.0059(1) 0 0 0.5U11 O 0.0067(2) U11 0.0087(3) -0.0011(1) - U23 0.0034(2)

60 o Table 4.5.4. Selected bond-lengths (Å) and angles ( ) for Cu3NiCl2(OH)6, compared with those in herbertsmithite (Braithwaite et al., 2004) and the subcell of paratacamite (Fleet, 1975) herbertsmithite gillardite Fleet (1975) M(1) = Zn M(1) = Ni M(1) = Cu M(2) = Cu M(2) = Cu M(2) = Cu M(1) – O 2.119(1) 2.0791(8) 2.11b M(2) – O 1.985(1) 1.9812(4) 1.98b M(2) – Cl 2.779(1) 2.7665(3) 2.78b O – M(1) – O a 102.93(3), 77.07(3), 180 O – M(2) – O a 98.34(5), 81.66(5), 180 O – M(2) –Cl a 97.81(2), 82.19(2), 180 O – H a 0.82(1) 1.14b H – Cl a 2.26(1) 1.95b O – Cl 3.071 3.049(8) 3.07b O – H – Cl ~166 162(2) 165.7b aNot given. bAverage distances in paratacamite with respect to split sites in space group R3 m.

No reflections corresponding to the paratacamite superlattice are present in the diffraction pattern of the gillardite structure. The OH-Cl system of hydrogen bonds supplements the Ni-O and Cu-O bonds in linking layers of metal-oxygen polyhedra, with an O-Cl distance of 3.049 Å. A selection of bond lengths and angles is given in Table 4.5.4, together with analogous values (where given) reported for herbertsmithite and the substructure of paratacamite, for comparison. The unit cell of gillardite is slightly smaller than that of herbertsmithite (a = 6.834(1), c = 14.075(2)

Å). This is consistent with the smaller radius of the Ni2+ ion, 0.69 Å, as compared to the Zn2+ ion, 0.74 Å, for coordination number 6 (Shannon, 1976).

A table of structure factors is given in the appendix (Table A.2). The

Crystallographic Information File (CIF) for gillardite (CSD-415857) is available in

Appendix Table A.3.

61 4.6 X-RAY POWDER DIFFRACTION

Powder X-ray diffraction data were recorded using a Philips PW1925-20 powder diffractometer (Ni-filtered Cu Kα radiation with pure Si as internal standard;

= 1.5418 Å). Table 4.6.1 lists powder diffraction data, together with those of herbertsmithite (Braithwaite et al., 2004) for comparison. Refined unit cell dimensions (Langford, 1973) from the powder diffraction data are a = 6.847(3), c =

13.931(8) Å, V = 565.5(4) Å3. The ten strongest lines in the X-ray powder diffraction pattern [d in Å(I)(hkl)] are 5.463(100)(101), 2.755(69)(113), 2.257(39)(204),

2.903(19)(201), 4.651(16)(003), 2.728(14)(202), 1.820(13)(303), 4.519(11)(102),

1.712(10)(220) and 3.427(8)(110). Indexing of the powder data was effected using a simulated pattern based on the single-crystal structure analysis (Kraus and Nolze,

1996a, b).

4.7 RELATIONSHIP OF GILLARDITE TO HERBERTSMITHITE

AND OTHER POLYMORPHS

Paratacamite, nominally Cu2Cl(OH)3, was reported by Frondel (1950) to be rhombohedral with hexagonal unit cell parameters a = 13.68, c = 13.98 Å, with a pronounced subcell corresponding to a' = a/2. The latter, space group R3 m, was considered to be correct by de Wolff (1953) but a single-crystal structure determination in space group R3 using the larger unit cell by (Fleet, 1975) confirmed the findings of Frondel (1950). A notable feature of the structure is the environment of the four non-equivalent copper ions. Three exhibit the usual tetragonally elongated

(4+2) coordination geometry of octahedral Cu(II), but the fourth has six symmetry- enforced equivalent bonds with an angular distortion from regular octahedral

62 Table 4.6.1. Powder X-ray diffraction data for gillardite and herbertsmithite. ______gillardite______herbertsmithitea___ Imeas Icalc dmeas/Å dcalc/Å hkl Imeas Icalc dmeas/Å 100 69 5.459 5.452 101 55 67 5.466 16 13 4.648 4.634 003 14 11 4.702

11 2 4.515 4.510 102 11 1 4.537 8 5 3.424 3.422 110 5 6 3.423 6 3 2.998 2.998 104 1 2 3.028 19 31 2.901 2.898 201 11 27 2.899 69 100 2.753 2.753 113 100 100 2.764 14 22 2.725 2.726 202 13 22 2.730 7 15 2.314 2.317 006 4 15 2.346 39 99 2.256 2.255 204 36 97 2.266 5 6 2.213 2.211 211 2 7 2.210 8 18 2.028 2.028 205 4 16 2.040 116 1 3 1.934 5 17 1.882 1.883 107 5 18 1.905 13 10 1.818 1.817 303 13 11 1.820 4 3 1.745 1.744 215 2 7 1.752 10 56 1.711 1.711 220 18 55 1.709 4 9 1.650 1.650 207 1 7 1.664 4 11 1.632 1.632 311 3 12 1.631 4 6 1.600 1.605 223 1 5 1.606 312 1 3 1.599 208 4 16 1.513 5 24 1.486 1.486 217 3 24 1.496 3 9 1.473 1.473 401 1 8 1.472 3 11 1.449 1.449 402 1 11 1.448 7 33 1.377 1.376 226 6 33 1.381 5 19 1.364 1.363 404 4 19 1.363 plus 10 lines to 1.020 aBraithwaite et al. (2004).

geometry. The careful work of Jambor et al. (1996), Grice et al., (1996) and

Braithwaite et al. (2004) has clarified ambiguities concerning the nature of polymorphs of nominal composition Cu2Cl(OH)3. It is now recognised that substitution at the site that is not tetragonally elongated is responsible for considerable structural variation. Paratacamite is rhombohedral, space group R3 , composition Cu3(Cu,M)Cl2(OH)6, with M = Zn, Co, Ni, etc., and with M occupying

⅓ to ½ of the above site (Braithwaite et al., 2004). The structure changes to that of

63 clinoatacamite, monoclinic, space group P21/n, when less than ⅓ of the Cu ions at that site are substituted by Zn ions (Grice et al., 1996; Jambor et al., 1996).

Herbertsmithite, Cu3(Zn,Cu)Cl2(OH)6, can adopt either of the rhombohedral space groups R3 or R3m for compositions near the transition stoichiometry. Where the site is filled or nearly filled with Zn it adopts the latter, corresponding to the subcell of

Fleet (1975).

Gillardite belongs to Strunz class 3.DA.10 (atacamite family; Strunz and

Nickel, 2001) and is the Ni-analogue of herbertsmithite, Cu3ZnCl2(OH)6 (Braithwaite et al., 2004). Gillardite is the species with ideal end-member composition

Cu3NiCl2(OH)6, forming a solid-solution series with Ni-rich paratacamite, with Cu occupying the Jahn-Teller distorted octahedral site in the lattice (at ½,0,0) and Ni occupying more than half of the more regular site (at 0,0,½). Methods for distinguishing gillardite and herbertsmithite from clinoatacamite and paratacamite on the basis of the powder X-ray diffraction record are dealt with elsewhere (Jambor et al., 1996; Braithwaite et al., 2004). Gillardite can be distinguished from herbertsmithite also by using powder X-ray diffraction if accurate data are available for d-spacings (Table 4.6.1). However, differences between observed and calculated intensities in the powder diffraction record for gillardite indicate the influence of preferred orientation effects. Calculated intensities for herbertsmithite (Kraus and

Nolze, 1996a,b), also given in Table 4.6.1, show that it too suffers from preferred orientation effects in powder diffraction. In fact, there is, as expected, a close correlation between calculated intensities for the two minerals. Gillardite can best be distinguished from nickel-bearing paratacamite and herbertsmithite by chemical analysis in conjunction with X-ray methods (unit-cell measurements). Kapellasite

(trigonal, space group P3 m1) is a recently described polymorph of herbertsmithite

64 (Krause et al., 2006). Its powder diffraction record is quite unlike that of herbertsmithite, and is somewhat similar to that of botallackite.

65 Chapter 5

THE BISMUTH MINERALS OF THE KINGSGATE,

NEW SOUTH WALES, DEPOSITS AND THE

SUPERGENE DISPERSION OF BISMUTH

5.1 INTRODUCTION

For such a rare element, the mineralogy of Bi is surprisingly diverse. Some

205 separate species that contain essential Bi are currently recognised by the IMA and of these 61 are secondary phases (Anthony et al., 1990, 1995, 1997, 2000, 2003;

Gaines et al., 1997). Primary phases vary from the comparatively “simple”, in terms of stoichiometry, to the exceedingly complex. Native bismuth and bismuthinite,

Bi2S3, are both common, but many complex Bi-bearing sulfosalts are known.

However, a survey of the literature (Anthony et al., 1990, 1995, 1997, 2000, 2003;

Gaines et al., 1997) reveals that the majority of the Bi minerals, whether of primary or secondary origin, are extremely rare and that only a small number are found repeatedly in Nature. For Bi minerals formed in the supergene environment, this has been borne out by studies of certain deposits in the New England region of New

South Wales (Rankin et al., 2001, 2002; Sharpe and Williams, 2004) and a survey of specimens housed in the collections of the Australian Museum, Sydney (see below).

Bismuth is estimated to have an average crustal abundance of 48 ppb

(Emsley, 1991), but is highly fractionated. Mafic to intermediate igneous rocks average 40 ppb, but rhyolite and averages are 900 and 270 ppb, respectively.

66 However, not all exhibit this degree of enrichment (Lueth, 1999).

Sedimentary rocks contain higher amounts, with shales having the greatest average

(0.26 ppm) and limestones the least (30 ppb) (Lueth, 1999). Coal (5 ppm on average) and other organic-rich materials are considerably enriched in Bi (Brandenstein et al.,

1960). Concentrations greater than 20 ppm have been reported for deep-sea manganese nodules (Ahrens and Erlank, 1978) and similar enrichment occurs in bauxite and sedimentary iron oxides (Goldschmidt, 1970). Kabata-Pendias (2001) gives an average Bi concentration in soils of 0.2 ppm, but this is difficult to reconcile with the data mentioned above. Bismuth is generally thought to have low mobility under normal surface pH and Eh conditions. This is reflected in data for natural aqueous solutions; sea water contains about 0.02 ppb and freshwaters less than 0.2 ppb, or less than 10-9 M Bi (Ahrens and Erlank, 1978; Madrakian et al., 2003).

Bismuth is, however, concentrated in a wide variety of ore types, principally associated with high-temperature acid intrusives, related skarn deposits and epithermal systems (Angino and Long, 1979; Baker et al., 2005; Lang and Baker,

2001). It is, together with Te, W, Sn and other accessory elements, often associated with gold mineralisation (Angino and Long, 1979; Baker et al., 2005). In the

Australian context, attention could be drawn to, in terms of accessory Bi mineralisation, the Cobar- style deposits (Stegman and Reynolds, 2005), Henty and

Mount Julia gold deposits, Tasmania (Callaghan, 2001), certain deposits in the

Western Australian shield (Hassan and Clarke, 2005) and the Cu-Au-Bi deposits of the Tennant Creek area, Northern Territory (Skirrow, 2002), although this group is indicative only, and is far from being comprehensive. In addition, bismuth minerals are important constituents, associated with Mo, W and Sn, of highly acidic and very rich (albeit of low tonnage) deposits of the eastern ranges of Australia (Plimer, 1975;

67 Weber et al., 1978). These have recently become the focus of intense exploration activity. Bi has been used extensively as a pathfinder element in geochemical exploration for a variety of such deposits and others (for example Angino and Long,

1979; Collins et al., 2004; Hale, 1981; Robertson et al., 2001)

In terms of the themes developed earlier in this thesis, it is clear that any proper understanding of the dispersion of Bi in the regolith will depend on an appreciation of its low temperature aqueous chemistry and a knowledge of the secondary Bi minerals that serve to buffer the element between the solid and solution states. The behaviour of the Bi in terms of its solution speciation as a function of pH is well-established (Baes and Mesmer, 1976; Norman, 1998; Smith and Martell,

1976; Thurston et al., 2005) and provides a first order, but simplistic, assessment of its mobility in pore solution in the regolith. However, virtually nothing is known of the chemistry of formation of secondary Bi species in the supergene zone or of their stabilities. This is a serious deficiency for the interpretation of Bi anomalies in the regolith formed as a result of the oxidation of primary Bi-bearing mineralisation.

This Chapter deals first with a survey of supergene Bi minerals from a number of Australian deposits, identified using powder XRD methods. Specimens were collected in the field and sourced from the collections of the Australian

Museum and Museum Victoria. This study has made possible an assessment of the most common secondary phases that are likely to be encountered in oxidised systems. Some emphasis has been placed on the deposits of the Kingsgate mining camp, New England region, New South Wales. This is in part due to recent bulk sampling in a small open cut by Auzex Resources Limited on what is probably a previously undiscovered branch of the Wolfram pipe. A number of specimens, including lead-bismuth sulfosalts and their oxidation products were unearthed and

68 provided an unprecedented opportunity to study fresh material from a deposit which had not been previously mined on the field. Other studies of unreported primary and secondary Bi (and Mo) mineralisation from other deposits to the south of the main

Kingsgate workings are described as a result of fieldwork and laboratory measurements. Finally, a simple geochemical model for Bi dispersion is developed on the basis of the most commonly encountered secondary species, using methods similar to those outlined in Chapter 2.

5.2 EXPERIMENTAL METHODS

5.2.1 Powder X-ray diffraction (XRD)

Powder X-ray diffraction (XRD) was commonly used for identification of minerals. For each specimen analysed, a small amount was ground to a fine powder using a mortar and pestle before being added to the sample stage. Measurements were carried out with a Philips PW1925-20 powder diffractometer operating at 40 kVand 30 mA using Ni-filtered Cu Kα radiation ( = 1.5405 Å). Pure Si was used as internal standard when unit cell parameters were to be determined. Detected X-rays were recorded between 5 and 75° 2θ, with a step size of 0.02° at a rate of 1.2° per minute. Identification of phases present in diffraction patterns was effected using

Diffraction Technology data processing software (Traces Version 6) with JCPDS-

ICCD database files.

5.2.2 Scanning electron microscopy (SEM)

Scanning electron microscopy was carried out using a JEOL 840

Microanalyzer, fitted with a thin window energy dispersive detector, controlled by

Moran Scientific acquisition and processing software. Energy dispersive

69 spectrometry (EDS) was used for qualitative/semi-quantitative elemental analysis.

The system was operated at an accelerating voltage of 20 keV and a beam current of

20 nA. SEM was also employed for high magnification secondary electron (SE) image capture. Samples were coated with carbon prior to analysis to prevent charging.

5.2.3 Electron microprobe analysis

Quantitative elemental analysis was carried out using a JEOL JXA 8600

Superprobe equipped with three wavelength dispersive spectrometers, analysing from Be to U, and a Kevex energy dispersive spectrometer analysing from Na to U, controlled by Moran Scientific software. Samples were embedded in epoxy resin, ground flat and polished with 1 m and 0.25 m diamond pastes before being carbon coated. Samples were analysed at an accelerating voltage of 20 keV and a beam current of 20 nA. Standards used for each element and minimum detection limits are given in Table 5.2.1.

Table 5.2.1 Element standards and minimum detection limits (MDL) for electron microprobe analyses. Element Standard MDL (wt%) S Iron disulfide 0.012 Cu Cu metal 0.060 Fe Iron disulfide 0.047 As Gallium arsenide 0.048 Se Cadmium selenide 0.141 Ag Ag metal 0.055 Sb Sb metal 0.046 Pb Lead sulfide 0.126 Bi Bi metal 0.097 Te Te metal 0.047

70 5.3 A SURVEY OF SECONDARY Bi AND Mo MINERALS FROM AUSTRALIAN COLLECTIONS

In order to gain information on the frequency of occurrence of secondary Bi

(and Mo) minerals, an XRD survey of specimens housed in the collections of the

Australian Museum and Museum Victoria was undertaken. Many of these had been incorrectly identified by, presumably, visual methods. Results are tabulated in Table

5.3.1. Reference to the table indicates that a number of rare species were found, but a pattern of distribution emerged. First, the association of Bi minerals with those containing Mo or W very commonly gives rise to koechlinite, Bi2MoO6, and russellite, Bi2WO6, in the oxidised zone, as noted elsewhere (Rankin et al., 2002;

Sharpe and Williams, 2004).

Bismite, Bi2O3, is a rare secondary phase and is usually found as a first oxidation product on native bismuth. It should be noted that Bi2O3 reacts with

CO2(g) under ambient conditions to give Bi2O2CO3 (Barreca et al., 2001). The most common secondary Bi minerals of all deposits are bismutite, Bi2O2CO3, and bismoclite, BiOCl. Preisingerite, Bi3O(AsO4)2OH, was found in several deposits, but

Table 5.3.1. Secondary Bi and Mo minerals identified in selected Australian depositsa.

NEW SOUTH WALES Bald Nob D30997b Bismutite Captains Flat M15216 Tetragonal bismuth oxide (new mineral) with bismutite, koechlinite, russellite Duckmaloi D30994 Bismutite Deepwater D21997 Bismutite, koechlinite, chekhovichite (Bi2Te4O11) D22221 Koechlinite, bismutite D22232 Bismutite, koechlinite D28072 Bismutite D37006 Koechlinite

71 Dundee D24224 Koechlinite D28509 Koechlinite, quartz D28510 Bismite, bismutite D28511 Koechlinite, bismutite D28512 Koechlinite, bismutite D35450 Zavaritskite (BiOF), bismite, bismutite, koechlinite D35450 Bismutite Elsmore D15631 Bismoclite D28050 Bismoclite Emmaville D18210 Russellite, bismutite Glen Eden D35884 Bismutite, koechlinite Glen Elgin D31404 Koechlinite, bismutite Gumble Flat D31051 Bismutite Kingsgate D2969 Bismutite, koechlinite D2970 Koechlinite D2971 Bismutite, koechlinite. D2973 Koechlinite D2974 Bismutite, bismite, koechlinite D2975 Preisingerite (Bi3O(AsO4)2OH), bismutite D7194 Koechlinite, bismutite D22004 Bismutite D30956 Bismutite, koechlinite D31339 Koechlinite D31340 , koechlinite, bismutite D31341 Wulfenite, koechlinite, bismutite D31343 Bismutite, preisingerite D31420 Bismutite D38036 Bismutite, chekhovichite, smrkovecite (Bi2O(PO4)OH) M30035 Bismutite, bismite M47205 Ferrimolybdite Nanima D18931 Bismutite D25033 Bismutite Mt Gipps D15637 Bismutite, kettnerite (CaBiOCO3F) Mt Razorback D35482 Bismutite Murrumbateman D30998 Bismutite Torrington D18209 Bismutite, russellite D28513 Bismutite D29744 Bismutite, russellite

72 D29745 Bismutite, russellite D29746 Russellite Whipstick D18930 Koechlinite D31052 Koechlinite Unknown D36340 Bismutite, russellite NORTHERN TERRITORY Alice Springs D30600 Bismutite Hatches Creek M18636 Bismutite Tennant Creek M48721 Bismutite; XRDMV M49700 Bismutite, bismite Wolfram Hill D51120 Bismutite, russellite QUEENSLAND Bamford D30972 Bismutite D30991 Koechlinite M7425 Ferrimolybdite; XRDMV Biggenden D31014 Bismutite, preisingerite D31016 Bismutite, preisingerite Chillagoe D18284 Bismutite D18284 Bismutite D18285 Bismutite D31026 Bismutite, preisingerite D31027 Bismutite M49613 Russellite; XRDMV Ukalunda D31017 Bismutite Halifax Bay D31012 Bismutite, koechlinite D31013 Bismutite, minor bismoclite Kaboonga D31045 Bismutite Malbon D30593 Bismutite Mt Hastings D31454 Bismutite Mt Shamrock D31048 Bismoclite Mt Wyatt D31035 Bismutite Wolfram Camp D31451 Koechlinite D31452 Koechlinite, bismutite

73 D31453 Russellite D51077 Bismutite, koechlinite M40932 Russellite SOUTH AUSTRALIA Balhanna mine M30249 Bismutite TASMANIA Forth River Gorge M47771 Ferrimolybdite; XRDMV Shepherd and Murphy mine D17161 Bismutite D31041 Bismutite, cannonite D31042 Bismutite, bismoclite D31043 Bismutite D31448 Bismutite VICTORIA Beechworth M15403 Bismutite; XRDMV M43565 Bismutite; XRDMV Bendoc D21624 Bismutite, zairite (Bi(Fe,Al)3(PO4)2(OH)6) Everton M38367 Ferrimolybdite M40860 Ferrimolybdite; XRDMV M42790 Ferrimolybdite M47686 Mendozavilite (Na(Ca,Mg)2Fe6(PO4)2(PMo11O39)(OH,Cl,)10·33H2O); XRDMV, chemical analysis Gombianbar Creek M274 Bismutite Maldon M7552 Bismutite M15402 Bismutite Mt Moliagul M39540 Ferrimolybdite M40723 Ferrimolybdite Mt Stanley M41176 Ferrimolybdite Pittong M47373 Koechlinite, bismoclite; XRDMV M47621 Koechlinite; XRDMV M47622 Bismoclite; XRDMV Thologolong M48714 Koechlinite; XRDMV Wangrabell M46176 Ferrimolybdite; XRDMV WESTERN AUSTRALIA Leinster M47710 Bismoclite

74 Mt Magnet D36109 Bismutite D36110 Bismutite Poona M49672 Russellite, bismutite; XRDMV Warriedar M35505 Ferrimolybdite a These were determined by XRD during the course of this study and are in addition to those previously reported by Rankin (2001, 2002) and Sharpe and Williams (2004). bSpecimen numbers beginning with D are from the Australian Museum and those with M from Museum Victoria. With respect to the latter, the note XRDMV refers to identification by powder XRD by W.D. Birch (personal communication).

no other secondary arsenate or related phosphates and vanadates were identified, although some of these are known to occur rarely as a result of other studies

(Anthony et al., 2000; Gaines et al., 1997; Rankin et al., 2002). It is also noted in passing that , BiCu6(AsO4)3(OH)6·3H2O, is quite common in the oxidised zones of complex base metal ores in small amounts (Anthony et al., 2000; Gaines et al., 1997). Further XRD investigations of more than 200 specimens collected from the Kingsgate deposits have revealed that cannonite, Bi2O(OH)2SO4, is not uncommon in the oxidised zone of the complex Old 25 pipe system and riomarinaite,

Bi(OH)SO4·H2O, is present in some of the samples collected from this pipe. In addition, cannonite is common in the oxidised zone of the Wolfram pipe. Though riomarinaite is very rare, its presence is highly significant in terms of the geochemical regime associated with the weathering of the deposits in the area (see below).

Taking all of these results into account, the pattern that emerges is that the common and key phases that need to be taken into account in developing a functional and reasonably sophisticated supergene geochemistry of Bi are bismite, bismoclite, bismutite, cannonite, koechlinite, russellite and mixite. Of these, reliable thermodynamic data are available only for bismite, bismoclite, bismutite, and a

75 congener of mixite, agardite-(Y); for the latter see McKinnon (2007). However, as a general proxy for supergene Bi mineralisation and the effects it exerts on the dispersion of the element, a preliminary but functional model may be developed based on bismite, bismoclite and bismutite. This is addressed below in Section 5.6.

5.4 THE Bi-Mo DEPOSITS OF KINGSGATE

The Mo-Bi deposits of Kingsgate, New South Wales, discovered in 1877, have produced some of the finest specimens of molybdenite and native bismuth ever found (Andrews, 1916; England, 1985; Lawrence, 1998). Mineralisation is essentially confined to pipe-like bodies of quartz in the Red Range hornblende- biotite granite near its contact with Permian siltstones (Weber et al., 1978). Primary mineralogy of the pipes has been discussed in detail by Lawrence and Markham

(1962). All of these reports concentrate on the area associated with major Mo-Bi production to the northwest of the Yarrow River, which lies some 20 km east southeast of the town of Glen Innes (Figures 5.4.1 to 5.4.4).

Figure 5.4.1. Location of Kingsgate mineral field, NSW

76

Figure 5.4.2. 1:2,500 map of the northern group of Kingsgate deposits. Map created using data from Brown (1995).

77

Figure 5.4.3. 1:5,000 map of the southern group of Kingsgate deposits. Created using data from Brown (1995).

78

Figure 5.4.4. Pipes mapped on the main Kingsgate field north of the Yarrow River (Garretty, 1944a,b).

79 More than 70 quartz pipes have been located in the area, but not all are mineralised.

Total production between 1877 and 1951 amounted to about 350 tonnes of molybdenite, 200 tonnes of bismuth and minor amounts of (Weber et al.,

1978).

5.4.1 Primary mineralogy

Early reports of the primary mineralogy of the deposits are sketchy, with a focus only on molybdenite, bismuth and bismuthinite (Andrews, 1906, 1916; Watt,

1898; Wilkinson, 1884). The report of Lawrence and Markham (1962) is the definitive study of the primary mineralisation of the field, supplemented by a description of maldonite, Au2Bi (Lawrence et al., 1998). A reported is given in Table 5.4.1. These publications have stood the test of time and no new primary phases have been found in the deposits until the present study.

Unfortunately, there is no detailed locality information for the minerals given in the two earlier publications listed above. All polished sections were sourced by

Lawrence from undocumented specimens in the Australian Museum. Recent trial open cutting of the Wolfram pipe, the first to be prospected on the field (Andrews,

1916), has permitted a study of the abundant Bi mineralisation that it hosts in association with molybdenite. A series of XRD and electron microprobe measurements has indicated that the Pb-Bi sulfosalts assemblage is much more complex than previously imagined.

The Wolfram pipe commences at a depth of about 10 m from the surface. No well developed crystals of sulfides except for molybdenite were found in the present workings, and only a few small quartz crystals were observed, indicating that vughs in the pipe are small and few in number. The majority of material collected was

80 Table 5.4.1. The primary minerals of Kingsgate (Lawrence and Markham, 1962; Lawrence et al., 1998). Molybdenite MoS2 Bismuth Bi Pyrrhotite Fe1-xS Pyrite FeS2 Chalcopyrite CuFeS2 Galena PbS Sphalerite ZnS Bismuthinite Bi2S3 Ikunolite Bi4S3 Arsenopyrite FeAsS Gudmundite FeSbS Joséite Bi4TeS2 Joséite-B Bi4Te2S Gold Au Maldonite Au2Bi SnO2 (Fe,Mn)WO4 Cosalite Pb2Bi2S5 Galenobismutite PbBi2S4 Pyrargyrite Ag3SbS3

primary mineralisation which occurs as small masses in quartz. Primary minerals present include molybdenite, ferberite, cassiterite, pyrite, pyrrhotite, arsenopyrite, chalcopyrite, galena, native bismuth, bismuthinite and a suite of lead bismuth sulfides (see below). Pyrrhotite and arsenopyrite, common in the dumps of the original wolfram pipe workings, were not present in large amounts in ore from the recent trial mining operation. Bulk sampling of run of mine material indicates average grades of Mo up to 0.73% and Bi up to 1.1%. There was very little evidence of secondary mineralisation present in the trial pit. XRD analysis of material from the original dump of the Wolfram pipe showed secondary phases including koechlinite, bismutite, wulfenite, anglesite and cannonite. The mineralogical study in this section of the thesis is focussed on the primary lead-bismuth mineralisation identified from material in the trial mining pit.

81 5.4.1.1 Bismuth Bi

Small masses of native bismuth (to 1 cm) were found filling interstices between quartz crystals. Such masses often have a dull grey appearance but exhibit the typical reddish-silver lustre of native bismuth when fractured. Thin growths of bismuth often coat molybdenite along cleavage planes (Figure 5.4.5). This may explain the common occurrence of the bismuth molybdate oxidation product koechlinite between blades of molybdenite (Figure 5.4.6). Several specimens were identified by X-ray diffraction consisting of native bismuth together with galena and bismuthinite. Further analysis by electron microscopy revealed native bismuth hosting inclusions of ikunolite, joséite, galenobismutite, bismuthinite and an unnamed Ag-rich Pb-Bi sulfide (Figures 5.4.7 and 5.4.8).

Figure 5.4.5. Thin growths of bismuth (tarnished gold in colour) in molybdenite.

82

Figure 5.4.6. Koechlinite between blades of molybdenite.

5.4.1.2 Bismuthinite Bi2S3 Bismuthinite is a relatively common bismuth sulfide mineral at Kingsgate. It frequently occurs in masses of coarse, parallel fibres. Bismuthinite also forms delicate nests of fine hair-like needles lining small quartz vughs (Figure 5.4.9).

Bismuthinite has a lustrous silver colour when freshly exposed, altering to dull grey when weathered. It is commonly coated by bismutite when oxidised (Figure 5.4.10).

Analysis by X-ray diffraction showed a number of bismuthinite specimens contained minor bismuth. Electron microprobe analyses showed bismuthinite intergrowths with galenobismutite (Figure 5.4.8).

83

Figure 5.4.7. Backscattered electron image of primary minerals from the Wolfram pipe. Bismuth (white) is associated with joséite (medium grey), and minor ikunolite (dark grey). Black areas contain galenobismutite, bismuthinite and an unnamed Ag- rich Pb-Bi sulfide mineral shown in brighter contrast in Figure 5.4.8. Field of view is 285 m.

Figure 5.4.8. Backscattered electron image of primary minerals from the Wolfram pipe, shown in brighter contrast than Figure 5.4.7. Bismuth is associated with joséite and ikunolite (all white) as well as galenobismutite (medium grey), bismuthinite (dark grey) and the Ag-rich Pb-Bi sulfide phases (black). Field of view is 285 m.

84

Figure 5.4.9. Fine hair-like bismuthinite needles. Field of view is 200 m.

Figure 5.4.10. Bismuthinite coated by bismutite from Jim Marshall’s Hole, Kingsgate, NSW. Field of view is 2 cm.

85 5.4.1.3 “Cannizzarite” Pb3Bi4S9

Electron microprobe analyses of phases occurring along edges and fractures in massive cosalite gave compositions similar to that of cannizzarite. The mineral was not however identified by XRD and it is most probable that this material represents a fine intergrowth of cosalite and galenobismutite.

5.4.1.4 Cosalite Pb2Bi2S5

Cosalite from Kingsgate is difficult to distinguish in hand specimens from the coarse bismuthinite described previously, and is much less common. It was identified as a minor phase associated with galena, galenobismutite and native bismuth by X- ray diffraction. Cosalite with distinctive sub-parallel inclusions of bismuth and bismuthinite is shown in Figure 5.4.11. XRD analysis of material from the Wolfram pipe has also identified intergrowths of cosalite with kobellite.

5.4.1.5 Galenobismutite PbBi2S4

Galenobismutite is relatively common, in small masses, associated with bismuth, bismuthinite and cosalite. It is easily distinguished from associated sulfides by its dull aluminium-like lustre and lack of fibrous habit.

5.4.1.6 Ikunolite Bi4(S,Te)3

Ikunolite was described as one of the rarest minerals occurring at Kingsgate by Lawrence and Markham (1962). It was identified in the present study by electron microprobe analysis as small inclusions in the related phase joséite, closely associated with bismuth and galenobismutite (Figure 5.4.7). Electron microprobe analyses of ikunolite are given in Table 5.4.2, and show up to 5.45 mol% substitution

86

Figure 5.4.11. Backscattered electron image of cosalite (medium grey), bismuth (white) and bismuthinite (dark grey). Field of view is 1 mm.

Table 5.4.2. Analyses (wt%) of ikunolite from the Wolfram pipe.a 1 2 3 4 AVG S 9.95 9.96 9.88 9.99 9.94 Sb 0.05 0.19 0.17 0.16 0.14 Pb 5.95 6.87 6.50 6.25 6.39 Bi 81.25 81.54 81.37 81.92 81.52 Te 1.99 1.97 2.06 2.25 2.10 Total 99.19 100.54 100.07 100.61 100.10 aAverage derived formula based on a total of 3 Te + S atoms is Bi3.58Pb0.28Sb0.01S2.85Te0.15.

87 of tellurium for , and significant substitution of lead for bismuth. This is consistent with the findings of Plimer (1977) who also identified Pb-rich ikunolite from Kingsgate, containing minor tellurium and selenium.

5.4.1.7 Joséite Bi4TeS2

Joséite was identified in the present study by electron microprobe analysis and XRD, and is associated with bismuth, galenobismutite, bismuthinite and minor ikunolite. Results of these analyses are listed in Table 5.4.3. Joséite and Joséite B have been reported in previous studies to occur widely at Kingsgate, albeit in small amounts, with similar associations (Lawrence and Markham, 1962). While the bismuth telluride tetradymite, Bi2(Te,S)3, is relatively common in other quartz pipes of Eastern Australia (Plimer, 1977), this phase does not appear to be present in the

Wolfram pipe.

Table 5.4.3. Analyses (wt%) of joséite from the Wolfram pipea. 1 2 3 4 AVG S 6.34 6.28 6.24 6.21 6.26 Pb 0.61 0.69 0.64 0.87 0.71 Bi 81.71 81.38 81.70 81.78 81.64 Te 11.89 11.83 11.89 12.18 11.95 Total 100.55 100.18 100.48 101.04 100.56 a Average derived formula based on a total of 3 Te + S atoms is Bi4.06Pb0.04Te0.97S2.03.

5.4.1.8 Kobellite Pb22Cu4(Bi,Sb)30S69

Kobellite occurs in relatively soft, grey-black, dense, fibrous masses that are generally less acicular than bismuthinite. It was identified in this study associated with both bismuthinite and cosalite, and represents the first reported occurrence of the mineral from the New England molybdenite-bismuth fields. Figure 5.4.12 is a secondary electron image showing aggregates of kobellite crystals. Kobellite was

88 identified in this study by XRD and electron microprobe. Powder XRD data for kobellite from the Wolfram pipe, composition (Cu1.12Fe0.88)Pb12(Bi7.89Sb6.11)S35, compared with data from JCPDF card 73-1137 are given in Table 5.4.4. Lines for the former are shown in bold for Irel >10 and for the latter with Irel >300 (note different scaling). Given that kobellite from the Wolfram pipe is very fibrous, preferred orientation effects are expected to be evident. The data of JCPDF card 73-1137 are calculated from single-crystal structure data. However, there is an excellent correlation between the two sets of data despite this fact and compositional differences at the detailed level (see below).

Figure 5.4.12. Secondary electron image of kobellite. Field of view is 200 m.

89 Table 5.4.4. Powder XRD data for kobellite to d = 2 Å from the Wolfram pipe compared with data from JCPDF card 73-1137, composition (Cu1.12Fe0.88)Pb12(Bi7.89Sb6.11)S35. Wolfram pipe JCPDF card 73-1137 d/Å Irel d/Å Irel 18.824 52 17.052 21 13.535 5 13.607 15 11.260 5 11.288 25 10.716 2 10.153 27 9.412 2 8.528 3 8.526 13 8.062 3 8.010 27 7.348 1 6.865 3 6.885 9 6.771 2 6.803 13 6.529 13 6.256 4 6.275 21 5.838 1 5.681 4 5.684 60 5.512 13 5.344 4 5.358 27 4.965 5 5.055 4 4.706 23 4.524 4 4.536 53 4.463 4 4.473 31 4.340 9 4.348 72 4.247 45 4.263 129 4.188 5 4.189 46 4.090 5 3.984 37 3.990 312 3.948 30 3.879 4 3.871 50 3.805 9 3.805 100 3.777 8 3.779 123 3.749 14 3.763 113 3.730 11 3.737 103 3.711 87 3.606 323 3.569 59 3.572 309 3.529 100 3.535 999 3.472 190 3.437 52 3.442 360 3.403 59 3.410 702 3.338 62 3.396 659 3.312 66 3.295 242 3.287 31 3.284 454 3.214 10 3.225 61 3.169 100 3.160 88 3.131 31 3.137 226

90 3.105 11 3.109 150 3.099 13 3.103 134 3.068 11 3.072 108 3.010 9 3.016 273 2.998 15 2.998 190 2.978 173 2.912 9 2.910 408 2.874 9 2.873 771 2.860 10 2.867 490 2.836 15 2.844 461 2.762 3 2.763 15 2.752 3 2.756 21 2.728 7 2.732 120 2.711 15 2.718 514 2.694 6 2.689 41 2.682 8 2.684 134 2.670 11 2.659 4 2.660 55 2.621 3 2.620 120 2.603 6 2.602 75 2.596 5 2.594 105 2.573 7 2.572 35 2.556 9 2.535 1 2.539 12 2.528 2 2.527 33 2.522 5 2.520 35 2.512 3 2.513 14 2.500 6 2.502 25 2.493 15 2.480 7 2.482 19 2.477 15 2.454 11 2.459 18 2.443 2 2.445 12 2.435 3 2.436 13 2.420 2 2.422 16 2.417 10 2.403 4 2.403 15 2.375 2 2.379 11 2.361 3 2.357 102 2.341 3 2.338 80 2.314 4 2.313 96 2.305 7 2.308 148 2.291 2 2.291 17 2.276 4 2.270 66 2.268 5 2.268 41 2.257 13 2.254 78 2.236 6 2.238 57 2.233 4 2.232 35 2.220 1 2.221 10 2.212 2 2.214 9 2.201 1 2.200 9

91 Electron microprobe analyses of kobellite show widely varying substitution for bismuth, with compositions ranging towards the Sb end-member tintinaite. Six electron microprobe analyses of kobellite gave analytical totals that varied from 100.951 to 102.17 wt%. Average element results (range given in parentheses) are S 18.06 (17.94-18.31), Cu 0.96 (0.88-1.01), Ag 0.61 (0.57-0.64), Sb

12.17 (11.57-12.74), Pb 35.91 (35.24-36.66), Bi 32.92 (32.72-33.29) and Fe 0.95

(0.80-1.05) wt%.

Zakrzewski and Makovicky (1986) have outlined a method for using analytical data to distinguish between members of the kobellite homologous series based on chemical composition. In particular, the method is useful to distinguish the kobellite from the izoklakeite sub-series. The general formula of the series is

+ 2+ 2+ 3+ T2x T2-2x AgyM8N-4-2x-2y M2N+10+2x+y S11N+13, where N is the order of the homologue (N = 2, kobellite, space group Pnnm, a = 22.82, b = 34.08, c = 4.02 Å;

N = 4, izoklakeite, space group Pnnm, a = 34.07, b = 37.98, c = 4.07 Å). In the formula, T+ and T2+ are tetrahedrally coordinated uni- and divalent ions, respectively,

2+ 3+ Agy is octahedrally coordinated Ag, M = Pb and M = Bi,Sb. Bracketing values for

N, which must be an integer, can be derived from atomic ratios for metals recalculated for a total of 56 per unit cell (S = 70 atoms per unit cell) in the case of kobellite. Use of the method of Zakrzewski and Makovicky (1986) gives

NCu(I) = 2.12 and NCu(II) = 1.61, for the case when T = Cu+Fe+Ag. Thus N = 2, confirming that the material is indeed kobellite. Assuming that the tetrahedral site is fully occupied, the average composition of kobellite from the

Wolfram pipe, based on S = 70 and M = 56 is

(Fe2.04Cu1.78Ag0.18)Σ4.00(Pb20.53Ag0.49)Σ21.02(Bi18.66Sb11.83)Σ30.49S70. This lies nicely between the theoretical end-member compositions (for the Sb-, Ag- and Fe-free

92 2+ + formulations) of Cu4Pb24Bi28S70 and Cu4Pb20Bi32S70, for Cu and Cu oxidation states, respectively.

5.4.1.9 Molybdenite MoS2

Molybdenite is common in the deposit. Single hexagonal crystals up to 7 cm across are embedded in quartz. It is sometimes associated with bismuth and galenobismutite.

5.4.1.10 Ag-rich Pb-Bi sulfides

Several electron microprobe analyses of Bi-Pb sulfides shown in Figure 5.4.7 gave high silver values, ranging up to 12.82 wt% (Table 5.4.5). Extensive solid solution phenomena displayed by the Pb-Bi-S system renders exact determination of the phases present quite difficult.

Tropochemical twinning and substitution of other chemical components represent a mechanism for the elaboration of structures and stoichiometries based upon simple lattices (Prodan et al., 1982, and references therein). As far as the present study is concerned, a number of Pb-Bi sulfide structures and compositions can be rationalised in terms of the galena lattice (Makovicky and Karup-Møller,

1972a,b; Otto and Strunz, 1968). These phases have the composition An-2BXn,

Table 5.4.5. Analyses (normalised wt%) of Ag-rich Pb-Bi sulfide grains from the Wolfram pipe. Grain 1 Grain 2 1 2 3 4 S 16.20 16.29 16.37 16.17 Ag 12.82 12.64 9.78 10.45 Sb 2.30 2.24 3.41 3.20 Pb 19.31 18.99 25.12 25.34 Bi 49.36 49.84 45.31 45.84 Total 100 100 100 100

93 where A and B fill octahedral and trigonal prismatic sites generated in a special way.

The coefficient n is the number of (113) planes in structural slabs between the twin planes. In the cubic galena lattice, all Pb ions are octahedrally coordinated. Twinning of one set of {113} planes in the galena lattice results in the loss of two octahedral sites in the twin plane and the generation of a trigonal prismatic site. Thus structural vacancies that arise from the substitution of 3Pb by 2Bi are eliminated. Ordered twinning and substitution in turn gives rise to a series of Pb-Bi sulfosalts of varying composition. These include aschamalmite and heyrovskýite, Pb6Bi2S9, lillianite and xilingolite, Pb3Bi2S6, cosalite, Pb2Bi2S5, cannizzarite, Pb3B4S9, galenobismutite,

PbBi2S4, mozgovaite, PbBi4S7, and ustarasite, PbBi6S10. PbS:Bi2S3 ratios vary in this series from 6:1 to 1:3 (shown in Figure 5.4.13) and other synthetic intermediates with no naturally occurring analogues are known. In principle, higher homologues of virtually infinite variety are possible. Many of the above phases are known to accommodate at least some Ag (Pring et al., 1999), but discrete mineral phases are formed by the ordered (for the most part) substitution of Ag+Bi for 2Pb in the archetypical An-2BXn lattices. Compositions of such phases from Wolfram pipe are shown in Figure 5.4.14.

The Ag-Pb-Bi sulfides developed in the same way as outlined above and those that have no simple, Ag-free structural counterparts are gustavite,

Ag3Pb5Bi11S24 (2.75:1), vikingite Ag8Pb5Bi13S30 (4.5:1), treasurite, Ag7Pb6Bi15S32

(5:1), eskimoite, Ag7Pb10Bi15S36 (6:1), and ourayite, Ag25Pb30Bi41S104 (10:1). A high- temperature, disordered phase, schirmerite, represents a solid solution that ranges in composition from AgPbBi3S6 (3:1) to Ag3Pb6Bi7S18 (6:1). Values in brackets refer to the PbS:Bi2S3 ratio for the reduced formula equivalents, taking into account the solid

94 S

Bismuthinite

Galena Ustarasite Cosalite Mozgovaite Mozgovaite Lillianite Cannizzarite Galenobismutite Galenobismutite Aschamalmite

Pb Bi

Figure 5.4.13. Ternary diagram showing a series of simple naturally occurring Bi-Pb sulfosalts.

solution substitution pattern 2Pb ≡ Ag+Bi. All of these phases have been characterised by single-crystal X-ray structure studies (Anthony et al., 1990). While the Ag-rich grains identified in the Pb-Bi mineralisation of the Wolfram pipe are too small and rare to isolate for powder XRD analysis, their probable natures can be deduced from the substitution relationship, 2Pb ≡ Ag+Bi(Sb). By use of this,

Grain 1 has a reduced chemical formula of Pb4.91Bi2.06S8, and most probably represents treasurite. Normalised analytical results give, on the basis of 32S pfu, a

95 S 100

Ustarasite Bismuthinite Mozgovaite Galenobismutite Galenobismutite Cannizzarite Cosalite Aschamalmite Galena 50 50 Pb + Ag Bi + Sb

Figure 5.4.14. Truncated ternary diagram for analyses of some Pb-Bi sulfosalts from the Wolfram pipe.

formula of Ag7.05Pb5.52Bi14.18Sb1.12□0.13S32. The lattice is slightly deficient in Pb as a result of a slight stoichiometric excess of Bi(Sb). Grain 2 has a reduced formula of

Pb4.91Bi2.06S8, and a less satisfactory, but acceptable formula of

Ag5.63Pb7.31Bi12.95Sb1.63□0.28S32, again based on normalised analytical results. Ag+Bi substitution in the Pb5Bi2S8 homologue is less extensive in this case. No other known sulfosalt can be satisfactorily fitted to the analyses, save for schirmerite, or possibly vikingite for grain 2. It is possible that both grains are members of the disordered series with PbS:Bi2S3 extending from 3:1 to 6:1, and the composition of grain 2 can

96 be recast to 30S pfu as Ag5.28Pb6.85Bi12.14Sb1.53S30. A complete resolution of this matter must await the discovery of sufficient material for an XRD study.

It is also worth noting that the present study has also found and unequivocally identified cosalite and galenobismutite mineralisation, together with bismuthinite and native bismuth (wires in quartz), in a small dump at the southern end of the Kingsgate property on the other side of the creek from Sach's Old 45. This is at (AGD84) 56J0401347E 6700370N and is probably from the pipe known as Jim

Marshalls Hole (Figure 5.4.3).

5.5 THE “LOST” MINES OF KINGSGATE

Despite the attention paid to pipes to the northwest of the Yarrow River, even the earliest reports of the field refer to other, similar deposits located a few km from

Kingsgate, south of the Yarrow River (Andrews, 1906; Watt, 1898; Wilkinson,

1884). These have been collectively grouped under the title of the Yarrow River deposits (Weber et al., 1978) but comparatively little attention has been paid to them in light of their limited production. In a search for quartz crystals suitable for electronic applications during World War II, the North Broken Hill Limited

Company identified 30 quartz pipes in the area (Figure 5.5.1). Aside from an isolated pipe on the Yarrow River, clusters of pipes were mapped as the Comstock and Pretty

Valley groups centred around 3991E 66983N and 4006E 66966N, respectively, on the Red Range 9238-II-N 1:25000 sheet (all subsequent grid references refer to this sheet). Two further groups lie between these near 4000E 66974N and 3997E 66976N

(Garretty, 1944a,b). This has led to some confusion in that the Comstock deposit is in fact associated with the Pretty Valley group (see below). MacDuff and Snow (1971)

97

Figure 5.5.1. Pipes mapped as the Comstock and Pretty Valley groups to the south of the Kingsgate field (Garretty, 1944a,b).

98 reported that 33 pipes were thought to occur in the area, but only a few had been identified as containing Mo and Bi mineralisation. These are Maurer’s Claim, the

Comstock mine (Yarrow Creek deposit 1) and the Gold Diggers Creek mine (Yarrow

Creek deposit 5); of these, Maurer’s Claim was apparently the main metal producer although more than 1.2 tonnes of molybdenite was reportedly won from the Gold

Diggers Creek mine and a total of 1.5 tonnes from the Comstock mine “with other pipes” (Brown, 1995).

Aside from Maurer’s Claim, reports of other work in the area are very sketchy. Wilkinson (1884) mentioned certain deposits in Parish Yarrow in the following terms:

“About 3 miles east of the Yarrow Creek head station, and about the same distance south-easterly from Kingsgate, is the Comstock Bismuth Company’s Mine. No work was being done here at the time of our visit; but we saw three pipe-veins of hard white crystalline quartz that had been opened for only a few feet from the surface. The shafts were partly filled with water, so that the exact size of the veins could not be measured; but the largest of them appeared to be about 6 feet 15 feet [sic] near the surface…These veins are also in granite, and distant about 200 yards from the slate formation. It is a somewhat remarkable feature that all the bismuth veins (eighteen) as yet found occur in the granite, within a short distance from the slate;…”

The description given cannot apply to Maurer’s Claim, which is immediately adjacent to the contact of the granite with metasediments. Furthermore, the distances place the Company’s operations some 2.5 km south of Maurer’s. The description does, however, correspond to known workings in Portions 20, 21 and 22, Parish

Yarrow. Templeton and Party applied for ML 34 to mine for bismuth at this locality in 1881.

The application was refused on 17.06.1884, with a covering note that ML 34 was included in MCP 81-267 and ACP 82-223 covering portions 21 and 22

99 (Sullivan, 1883). Andrews (1916) reported information communicated by Mr

Warden Perry that deposits containing bismuth and molybdenite also existed on

Portions 101 and 102, Parish Yarrow, and that other payable deposits existed on

Portions 20, 21, 22 and 23. In these, only gold was reserved by the Crown. Brown

(1995) locates the Comstock mine in Portion 21, Parish Yarrow, and this is apparently the same as the Yarrow Creek deposit of MacDuff and Zerwick (1971a).

An old group of workings at 400619E 6696567N is located in the centre of the

Portion, but no mineralisation other than quartz was found during the present study.

Brown (1995) mentions the presence of coarse molybdenite rosettes up to 1 cm in diameter. However, waste rock associated with a rehabilitated shaft at 400600E

669638N consists of milky quartz bearing the impressions of molybdenite books up to 5 cm across and 1 cm thick, and isolated molybdenite flakes are present in levelled dump material. It is possible that it was this shaft that was mined by the Comstock

Bismuth Company for Mo and Bi. The Yarrow Creek deposit 4 (Brown, 1995) or

North Yarrow Creek (MacDuff and Zerwick, 1972) at 400021E 6697320N was similarly found to be devoid of any metallic mineralisation. MacDuff and Zerwick

(1972) noted that “it appears that most of the pipes and veins in this area were worked for quartz crystal.” The Gold Diggers Creek mine lies still further to the north in Portion 101 at 399620E 6697720N. Recent excavations, presumably by fossickers, have exposed a vein or pipe of quartz. A few smoky quartz crystals up to

5 cm in length were found in the dump, but again no trace of molybdenite was seen.

Maurer’s Claim is located 24 km southeast of Glen Innes at 399090E

6698260N. Smith (1913) mentioned the deposit held by G.P. Maurer and party as being situated on Portion 19, Parish Yarrow; County Gough and consisting of private land comprising 9 acres covered by an Authority to Enter and 1 acre detached. The

100 mineral mined was molybdenite in granite, with the lode (variously described as a

“pipe?” or “vein?”) striking northeast and dipping northwest. At that time the length and depth of the workings were 20 feet and about 20 feet, respectively. Output was stated as being 1 ton 3 cwt 15 lbs of 97% molybdenite valued at £174.12.0; only one man was at work and prospecting aid had been applied for. In addition, Smith (1913) noted that old workings on another line were said to be 60 feet deep and full of water. Later reports are consistent with these observations. Elsewhere it was noted that “a fair amount of sinking and driving” had been carried out by Maurer and party during 1912 (Osborne, 1975). Andrews (1916) reported that the Dodger Claim, also known as Maurer’s Claim, was covered by PML1 (1 acre), and Authority to Enter

349 (approximately 17 acres) surrounding it, in Parish Yarrow, County Gough.

When visited by Andrews in 1915, the workings were filled with water and could not be inspected. Aid from the Prospecting Vote was granted to Maurer and Party in

1916 to sink.

Andrews (1916) provided a sketch map (Figure 5.5.2) and described the deposit based on notes supplied by Maurer. Four quartz-rich pipes were located near the contact of the granite with metasediments (“claystone”). No. 1 was 30 feet long and 8 feet wide at surface and had been developed to a depth of 50 feet. Bismuth and molybdenite were exposed at the bottom and Maurer had sold 7 cwt 46 lbs of molybdenite concentrates recovered from it for £115. No. 2 had been sunk on for about 10 feet and molybdenite was present in the bottom covering an area of about 8 x 12 feet. No. 3 was described as a pipe mined to a depth of 60 feet, at which the bottom showed molybdenite in granular quartz. Maurer claimed that a ton of molybdenite had been recovered from it but Andrews noted that this was hard to estimate as another party had produced molybdenite at this locality in 1902, but had

101

Figure 5.5.2. Sketch plan of Maurer’s Claim (Andrews, 1916).

not kept any records (the party that worked the lease has not been identified; Brown,

1995). Pipes 1 to 3 were clustered together and may represent branches of a complex pipe; Pipe 4 was about 50 yards from No.2 and contained bismuth and molybdenite in altered granite. No. 4 was about 10 feet in diameter and had been worked to a depth of 15 feet. Maurer took up the lease in 1912 and relinquished it in 1921

(Brown, 1995). D.J. Hartwell held the lease from 1942 to 1948 (Brown, 1995) and the full extent of the workings was established during World War II, when they were dewatered during a search for quartz crystals suitable for electronic purposes

(Booker, 1943; Garretty, 1943). No. 1 was sunk vertically for 27 feet, driven 20 feet on a bearing of 155o, then sunk vertically for 9 feet on a vein of massive quartz. No.

2 was sunk vertically for 20 feet on a vein of crystallised quartz about 6 inches wide, then on an underlay of 45o bearing 250o for 10 feet. The vein cut out at 22 feet. No. 3 was sunk vertically for 15 feet, on an underlay of 45o bearing 120o for 15 feet, and finally for another 30 feet vertically. The workings followed a pipe about 8 feet

102 across and composed of milky and lode quartz carrying molybdenite. No. 4 was a vertical shaft sunk on a narrow quartz vein to a depth of 58 feet. The vein cut out at about 25 feet. A fifth working was described as comprising an underlay (30o) shaft

15 feet deep sunk on lode quartz that had cut out in the face. It is worth noting that the presence of molybdenite was mentioned only in connection with the No. 3 pipe.

5.5.1. Minerals from Maurer’s Claim

During his inspection of Maurer’s Claim, Andrews (1916) noted heaps of massive and crystallised quartz carrying molybdenite flakes scattered on the dumps.

Some of the quartz crystals were doubly terminated. Crystals matching this description were recovered during fieldwork and an example is shown in Figure

5.5.3.

Figure 5.5.3. Doubly terminated smoky quartz crystal from Maurer’s Claim, 4.5 cm long.

103 An unusual habit of quartz from “Maurer’s molybdenite pipe” was reported by Smith (1926). Flat, transparent, four-sided crystals, some doubly terminated, lying loose on the bottom of a vugh were recovered; terminations were effected by four pyramidal faces. Examples of this habit of quartz were also recovered during fieldwork in the area and an example is shown in Figure 5.5.4.

Brown (1995) states that the deposit, “a major producer” in the area, carried molybdenite and native bismuth. Recent fossicking by unknown parties on the dumps has yielded smoky quartz crystals up to 32 cm in length carrying bismuthinite inclusions up to 5 cm in size (Heart of the Bay International Crystals, 2006). The specimen reproduced as Figure 6 in Lawrence (1998) and shown below in Figure

5.5.5 was probably one of the specimens recovered from Maurer’s and during recent fieldwork a similar specimen consisting of a somewhat milky quartz crystal enclosing a fan of bismuthinite crystals 2 cm in length was found. Aside

Figure 5.5.4. Flattened quartz crystal from Maurer’s Claim, 6 x 5 x 0.7 cm. The crystal is markedly flattened on m (101 0). Terminations at the top of the crystal are effected by r (1011) and z (0111).

104

Figure 5.5.5. Fans of bismuthinite crystals completely enclosed in a 16 cm long quartz crystal. Photo: Minerama Inc. Specimen: W. Somerville.

from this, Bi mineralisation at Maurer’s is very rare, in line with all of the pipes of the Comstock and Pretty Valley groups. A few mm sized grains of native bismuth and bismuthinite were found in clear and milky quartz on the dumps; these were not associated with molybdenite. The latter mineral must have been of principal economic interest. Rosettes of molybdenite up to 2 cm across in clear and smoky quartz are present in the dumps and some individual crystals were recovered (Figure

5.5.6).

Secondary minerals are virtually absent in the deposit. No secondary Bi minerals were found. Some alteration of molybdenite to ferrimolybdite (Figures 5.5.7 and 5.5.8) was evident and such material must have come from the uppermost sections of the pipes. Its occurrence is indicative of a highly acid oxidising environment, as is the case on the main Kingsgate field (see below).

105

Figure 5.5.6. Single hexagonal molybdenite crystal, 13 mm across, in quartz from Maurer’s Claim. Photo: Jim Sharpe.

Figure 5.5.7. Felted fibres of yellow ferrimolybdite crystals in quartz from Maurer’s claim. Field of view is 1.5 cm.

106

Figure 5.5.8. Secondary electron image of ferrimolybdite from Maurer’s claim. Field of view is 833 m.

5.6 A GEOCHEMICAL MODEL FOR BISMUTH IN THE

SUPERGENE ENVIRONMENT

5.6.1. The pH regime of the supergene zone at Kingsgate

Molybdenum possesses a similarly exotic supergene mineralogy, but not one that is as elaborate as that of Bi. Thirty species are currently recognised by the IMA and most of them are extremely rare (Anthony et al., 1990, 1995, 1997, 2000, 2003;

Gaines et al., 1997). Normal molybdate salts such as , CaMoO4, and wulfenite, PbMoO4, are the most common, and both are known in small amounts

107 from Kingsgate (England, 1985). Basic Cu(II) molybdates occur in certain porphyry

Mo deposits and several uranyl molybdates are associated with oxidised, U-rich ores.

No carbonates are known and the simple oxides , MoO3, and sidwillite,

MoO3·2H2O, are very rare, despite the frequent attribution of the former to the

“molybdic ochres” found in many oxidised settings. It has been more recently recognised that much material identified in the past as molybdite or molybdic ochre is in fact ferrimolybdite, Fe2(MoO4)·8H2O. Ferrimolybdite can only form at pH values less than about 3 and is thus characteristic of acid oxidising conditions

(Sarafian and Furbish, 1965). Between about pH 3 and 3.5, the more basic phase bamfordite, FeMo2O6(OH)3·H2O, is formed but the narrow pH range associated with its stability (Sarafian and Furbish, 1965) limits its distribution in Nature; to date it is known only from the type locality (Birch et al., 1998). These observations, together with a knowledge of the occurrence of polymolybdate species, are important geochemical clues with respect to the dispersion of Mo in the supergene zone. Like

2- tungstate(VI), MoO4 polymerises under acid conditions if sufficiently high concentrations are reached (Baes and Mesmer, 1978) and molybdate can be dispersed under basic conditions in ground waters. However, when molybdenite oxidises together with bismuth or minerals, the very insoluble Aurivillius phases koechlinite, Bi2MoO6, and russellite, Bi2WO6, are formed (Aurivillius phases are salts consisting of positively charged Bi-O layers with anions and sometimes water molecules sandwiched between them). These are very common secondary minerals in the New England Bi deposits.

It has hitherto been supposed (England, 1985) that ferrimolybdite is the common oxidation product of molybdenite, MoS2, at Kingsgate, but this is not the case; most of the yellow “molybdic ochres” associated with the field have been

108 shown to be koechlinite. This too is significant in understanding the geochemistry of the oxidised zone in this setting and its bearing on the dispersion of Bi and Mo under weathering conditions. Other identified phases are rarer at Kingsgate, but some are very significant in terms of the geochemical setting for their formation. Notable among these are cannonite, Bi2O(OH)2SO4, and riomarinaite, BiOHSO4·2H2O, both being comparatively abundant in the Old 25 and Wolfram pipes. In general, the supergene zone at Kingsgate is acidic. The Bi-Mo deposits of Kingsgate are virtually devoid of carbonates, aside from the very insoluble Bi species bismutite. The sole pipe reported to carry primary carbonate mineralisation is Goodwin’s Pipe, in which calcite formed the cement for fractured quartz and occurred as crystals a few cm long lining vughs (England, 1985). Drusy films of calcite on or filling joints between quartz crystals and fragments may still be collected on the dumps. No other carbonate minerals have been found elsewhere on the field. Given the above data, and the geochemical considerations below, the occurrence of bismite at Kingsgate, and elsewhere, must be due to its crystallisation in local microenvironments that were CO2-depleted; alternatively, it may form as a metastable phase. In any event, bismite is a rare mineral at Kingsgate (England, 1985; Sharpe and Williams, 2004).

Oxidation of molybdenite in a quartz-dominated gangue free of carbonate inevitably leads to very acidic conditions. This is evident from an inspection of the stoichiometry of the process as shown in equation (5.1).

2- 2- + MoS2(s) + 9/2O2(g) + 3H2O(l) → MoO4 (aq) + 2SO4 (aq) + 6H (aq) (5.1)

Oxidation of accessory pyrrhotite and arsenopyrite, in particular, followed by hydrolysis of Fe3+(aq), will further acidify the system. In the absence of a carbonate

109 gangue, protons will either be flushed from the supergene zone or react with feldspars to yield clays, which are conspicuous constituents of the upper sections of the Kingsgate pipes. In related deposits, such as at Elsmore, acid-catalysed

2- polymerisation of MoO4 gives rise to betpakdalite,

[Mg(H2O)6]Ca2(H2O)13[Mo8As2Fe3O36(OH)](H2O)4 (Rankin et al., 2001, 2002). At

Kingsgate, this species has not been observed, but conditions were certainly acid enough to give rise to ferrimolybdite in the oxidised zones of Bi-poor pipes.

Significantly, the occurrence of minor riomarinaite with cannonite, especially from the Old 25 and Wolfram pipes, proves that the pH of mineralising solutions in the upper sections of the pipe reached levels below 1.1. This is the pH that must be achieved for cannonite to be transformed to riomarinaite (Golič et al., 1982; Grauer and Lazarini, 1982).

5.6.2. A model for Bi solubility and dispersion

Two basic carbonates of bismuth are known. These are bismutite, Bi2O2CO3, and a synthetic phase of composition Bi4O4CO3(OH)2. Taylor et al. (1984) studied, inter alia, the stability of these phases, relative to that of bismite, α-Bi2O3, in terms of p(CO2). At 298.2 K, lg p(CO2) equals -5.5 ±1.0 when bismite is in equilibrium with Bi4O4CO3(OH)2, and equals -4.4 ±1.0 when Bi4O4CO3(OH)2 is in equilibrium with bismutite. Values of Gibbs free energies of formation for both basic carbonates were derived.

In order to place these values on the same basis as that chosen for our

o extended data set, ΔfG values have been recalculated using values for H2O(l),

CO2(g) and Bi2O3(s) at 298.2 K taken from Robie and Hemingway (1995).

o This yields values of ΔfG (Bi2O2CO3,bismutite,s,298.2 K) and

110 o -1 ΔfG (Bi4O4CO3(OH)2,s,298.2 K) of -916.2 ±7.5 and -1649.9 ±9.0 kJ mol , respectively. It is immediately apparent that Bi4O4CO3(OH)2 forms only at p(CO2) values below ambient (10-3.5) and that bismite is thermodynamically unstable with respect to Bi4O4CO3(OH)2 under ambient conditions when H2O is present or with

-5.5 respect to bismutite whenever p(CO2) > 10 . Bismutite is thus the stable phase under ambient conditions with respect both to Bi4O4CO3(OH)2 and bismite. This is in line with the observation that Bi2O3 exposed to air undergoes surface carbonation and that preparation of pure Bi2O3 requires heating samples in an air stream at elevated temperatures (Barreca et al., 2001; Levin and Roth, 1964).

Leaving aside rare secondary bismuth minerals and those that contain other metal or metalloid constituents, a first approach to an understanding of the behaviour of Bi in the supergene environment can be based on bismutite, the most common secondary Bi mineral, and bismoclite, BiOCl. For this purpose, the phase diagram shown in Figure 5.6.1 has been constructed. A value for

o -1 ΔfG (BiOCl,bismoclite,s,298.2 K), of -322.1 kJ mol , was taken from Kaye and

Laby (1995). The equilibrium condition for equation (5.2) was then calculated using

o - -1 the data listed above, with ΔfG (Cl ,aq,298.2 K) = -131.2 kJ mol (Robie and

Hemingway, 1995), and this gives equation (5.3).

+ - Bi2O2CO3(s) + 2H (aq) + 2Cl (aq) ⇋ 2BiOCl(s) + CO2(g) + H2O(l) (5.2)

- pH = 8.50 – ½lg p(CO2) + lg a(Cl ) (5.3)

3+ - Bi (aq) + 3e ⇋ Bi(s) (5.4)

111 The quoted errors in p(CO2) for the stability of bismite and bismutite versus

Bi4O4CO3(OH)2 (Taylor et al., 1984) correspond to an error of 0.5 pH units.

Dissolved species in equilibrium with bismutite and bismoclite can then be evaluated. For this purpose, the equilibrium data of Table 5.6.1 has been taken from

o 3+ the literature. In the calculations, a value for ΔfG (Bi ,aq,298.2 K) is needed.

Lovreček et al., (1985) give the standard electrode potential, Eo, at 298.2 K for

o 3+ equation (4) as 0.3172 ±0.0006 V; this corresponds to ΔfG (Bi ,aq,298.2 K) =

+91.8 ±0.2 kJ mol-1 and this is the value adopted here. It should be noted that uncertainties in the value cancel out in calculations of dissolved Bi(III) species. The following is given as an example. LgK (298.2 K) for equation (5.4) is derived from

o ΔfG data for constituent species given above and equation (5.7) is the sum of (5.5) and (5.6).

+ 3+ - BiOCl(s) + 2H (aq) ⇋ Bi (aq) + Cl (aq) + H2O(l) lg K = -7.99 (5.5)

3+ 2+ + Bi (aq) + H2O(l) ⇋ BiOH (aq) + H (aq) lg K = -1.11 (Table 1) (5.6)

+ 2+ - BiOCl(s) + H (aq) ⇋ BiOH (aq) + Cl (aq) lg K = -9.10 (5.7)

Calculations were carried out over the pH range from 0 to 9 giving activities for each bismuth species in solution in equilibrium with bismoclite and bismutite (Figure

5.6.1). Separate calculations for a(Cl-) equal to 10-1 (comparatively saline conditions)

-4 -3.5 and 10 (simulating rain water-flushed conditions) and p(CO2) equal to 10

(normal atmospheric levels) and 10-2.5 (simulating soil atmospheric levels) were performed. No correction for ionic activity coefficients were made; such corrections

112 Table 5.6.1. Data used to calculate species distributions in solutions at equilibrium with solid phases at 298.2 K (I = 0). State terms have been omitted for simplicity. Equation lg K Ref.a 3+ 2+ + Bi + H2O ⇋ BiOH + H -1.11 [1] 3+ + + Bi + 2H2O ⇋ Bi(OH)2 + 2H -3.30 [1] 3+ o + Bi + 3H2O ⇋ Bi(OH)3 + 3H -8.21 [1] 3+ - + Bi + 4H2O ⇋ Bi(OH)4 + 4H -21.11 [1] 3+ 6+ + 6Bi + 12H2O ⇋ Bi6(OH)12 + 12H -0.33 ±0.1 [2] 6+ 7+ + 1.5Bi6(OH)12 + 2H2O ⇋ Bi9(OH)20 + 2H -3.5 ±0.1 [2] 7+ 6+ + Bi9(OH)20 + H2O ⇋ Bi9(OH)21 + H -3.2 ±0.1 [2] 3+ - 2+ b Bi + Cl ⇋ BiCl 2.4 [2,3] 3+ - + b Bi + 2Cl ⇋ BiCl2 3.5 [2,3] 3+ - o b Bi + 3Cl ⇋ BiCl3 5.4 [2,3] 3+ - - b Bi + 4Cl ⇋ BiCl4 6.1 [2,3] 3+ - 2- b Bi + 5Cl ⇋ BiCl5 6.7 [2,3] 3+ - 3- b Bi + 6Cl ⇋ BiCl6 6.6 [2,3] a[1]: van der Lee and Lomenech (2004); [2]: Lovreček et al., (1985); [3]: Smith and Martell (1976). bT = 293.2 K (I = 2); Lovreček et al. (1985) note that the temperature variation introduces an error, but consider it to be practically negligible. pH 024681012 0

-1

-2

) Bismoclite - (Cl a lg -3 Bismutite

-4 10-1 10-1.5 p (CO2) 10-2.5 10-3.5 -5

Figure 5.6.1. Stability field diagram for bismoclite and bismutite. The fields are limited by lines corresponding to different p(CO2) values, as shown.

113 would be very small for conditions when a(Cl-) = 10-4 and when considering soil water geochemical regimes in which the main aqueous input is rainwater. High relief at Kingsgate would serve to prevent deep ground water interaction with the present oxidised zone. Results are tabulated in Tables 5.6.2 to 5.6.5.

It is appropriate to limit considerations of Bi(III) solubility to pH conditions that obtain in the Kingsgate regolith. Soils covering mineralised areas are predominantly shallow, with an umbric A horizon formed over acid siliceous rocks.

For this environment, pH is expected to vary between about 4 and 6.5, with a median of about 5. Soils covering granites of the New England region are known to have pH values of less than 5.5 in all horizons (Dolling et al., 2001). Inspection of the data of

Tables 5.6.2 to 5.6.5 shows that the maximum Bi concentration is soil water in equilibrium with the secondary Bi minerals at pH 5 is about 10-7 M (ignoring activity corrections), when negligible Cl-(aq) ion is present, and bismutite is the thermodynamically stable phase. This in turn corresponds to a total solution Bi load of only 0.1 ppb. As a(Cl-) increases, total solution Bi is depressed further. The presence of less soluble phases such as koechlinite, preisingerite and cannonite will serve to limit Bi solution levels still further. In addition, soil gas concentrations of

CO2 can reach partial pressures an order of magnitude higher than those considered here, as the result of biological activity (Appelo and Postma, 1993). This would result in an extension of the stability field for bismutite and further lowering of solution Bi concentrations. Put simply, the rate of dissolution of Bi minerals and chemical dispersion of the element in the regolith is predicted to be very slow in comparison with most base metals.

114

- -1 -3.5 Table 5.6.2. Total bismuth in solution at equilibrium with bismoclite and bismutite when a(Cl )= 10 p(CO2)= 10 (absence of data refers to cases when the calculated activity is less than 10-13). ______Species pH ______0 1 2 3 4 5 6 7 8 9 ______BiOH2+ 7.94x10-9 7.94x10-10 7.94x10-11 7.94x10-12 7.94x10-13 + -11 -11 -11 -11 -11 -11 -11 -11 -11 -11 Bi(OH)2 5.13x10 5.13x10 5.13x10 5.13x10 5.13x10 5.13x10 5.13x10 5.13x10 5.13x10 5.13x10 0 -13 -12 -11 -10 -9 -8 -7 Bi(OH)3 6.31x10 6.31x10 6.31x10 6.31x10 6.31x10 6.31x10 6.31x10 - -13 -11 Bi(OH)4 7.94x10 7.94x10 6+ Bi6(OH)12 7+ Bi9(OH)20 6+ Bi9(OH)21 BiCl2+ 2.57x10-6 2.57x10-8 2.57x10-10 2.57x10-12 + -6 -8 -10 -12 BiCl2 3.24x10 3.24x10 3.24x10 3.24x10 o -5 -7 -9 -11 -13 BiCl3 2.57x10 2.57x10 2.57x10 2.57x10 2.57x10 - -5 -7 -9 -11 -13 BiCl4 1.29x10 1.29x10 1.29x10 1.29x10 1.29x10 2- -6 -8 -10 -12 BiCl5 5.13x10 5.13x10 5.13x10 5.13x10 3- -7 -9 -11 -13 BiCl6 4.07x10 4.07x10 4.07x10 4.07x10 Bi3+ 1.02x10-7 1.02x10-9 1.02x10-11 1.02x10-13 Σ 5.01x10-5 5.01x10-7 5.14x10-9 1.10x10-10 5.88x10-11 1.14x10-10 6.82x10-10 6.36x10-9 6.32x10-8 6.31x10-7 ______

115

- -1 -2.5 Table 5.6.3. Total bismuth in solution at equilibrium with bismoclite and bismutite when a(Cl )= 10 p(CO2)= 10 (absence of data refers to cases when the calculated activity is less than 10-13). ______Species pH ______0 1 2 3 4 5 6 7 8 9 ______BiOH2+ 7.94x10-9 7.94x10-10 7.94x10-11 7.94x10-12 7.94x10-13 + -11 -11 -11 -11 -11 -11 -11 -11 -11 -11 Bi(OH)2 5.13x10 5.13x10 5.13x10 5.13x10 5.13x10 5.13x10 5.13x10 5.13x10 5.13x10 2.92x10 0 -13 -12 -11 -10 -9 -8 -7 Bi(OH)3 6.31x10 6.31x10 6.31x10 6.31x10 6.31x10 6.31x10 3.59x10 - -13 -11 Bi(OH)4 7.94x10 4.52x10 6+ Bi6(OH)12 7+ Bi9(OH)20 6+ Bi9(OH)21 BiCl2+ 2.57x10-6 2.57x10-8 2.57x10-10 2.57x10-12 + -6 -8 -10 -12 BiCl2 3.24x10 3.24x10 3.24x10 3.24x10 o -5 -7 -9 -11 -13 BiCl3 2.57x10 2.57x10 2.57x10 2.57x10 2.57x10 - -5 -7 -9 -11 -13 BiCl4 1.29x10 1.29x10 1.29x10 1.29x10 1.29x10 2- -6 -8 -10 -12 BiCl5 5.13x10 5.13x10 5.13x10 5.13x10 3- -7 -9 -11 -13 BiCl6 4.07x10 4.07x10 4.07x10 4.07x10 Bi3+ 1.02x10-7 1.02x10-9 1.02x10-11 1.02x10-13 Σ 4.01x10-5 5.01x10-7 5.14x10-9 1.10x10-10 5.88x10-11 1.14x10-10 6.82x10-10 6.36x10-9 6.32x10-8 3.59x10-7 ______

116

- -4 -3.5 Table 5.6.4. Total bismuth in solution at equilibrium with bismoclite and bismutite when a(Cl ) = 10 p(CO2)= 10 (absence of data refers to cases when the calculated activity is less than 10-13). ______Species pH ______0 1 2 3 4 5 6 7 8 9 ______BiOH2+ 7.94x10-6 7.94x10-7 7.94x10-8 7.94x10-9 7.94x10-10 7.94x10-11 7.94x10-12 1.43x10-13 + -8 -8 -8 -8 -8 -8 -8 -9 -10 -11 Bi(OH)2 5.13x10 5.13x10 5.13x10 5.13x10 5.13x10 5.13x10 5.13x10 9.23x10 9.23x10 9.23x10 0 -13 -12 -11 -10 -9 -8 -7 -6 -6 -6 Bi(OH)3 6.31x10 6.31x10 6.31x10 6.31x10 6.31x10 6.31x10 6.31x10 1.14x10 1.14x10 1.14x10 - -12 -11 -10 Bi(OH)4 1.43x10 1.43x10 1.43x10 6+ Bi6(OH)12 7+ Bi9(OH)20 6+ Bi9(OH)21 BiCl2+ 2.57x10-06 2.57x10-08 2.57x10-10 2.57x10-12 + -09 -11 -13 BiCl2 3.24x10 3.24x10 3.24x10 o -11 -13 BiCl3 2.57x10 2.57x10 - -14 BiCl4 1.29x10 2- BiCl5 3- BiCl6 Bi3+ 1.02x10-4 1.02x10-6 1.02x10-8 1.02x10-10 1.02x10-12 Σ 1.13x10-4 1.89x10-6 1.41x10-7 6.00x10-8 5.84x10-8 1.14x10-7 6.82x10-7 1.15x10-6 1.14x10-6 1.14x10-6 ______

117

- -4 -2.5 Table 5.6.5. Total bismuth in solution at equilibrium with bismoclite and bismutite when a(Cl ) = 10 p(CO2)= 10 (absence of data refers to cases when the calculated activity is less than 10-13). ______Species pH ______0 1 2 3 4 5 6 7 8 9 ______BiOH2+ 7.94x10-6 7.94x10-7 7.94x10-8 7.94x10-9 7.94x10-10 7.94x10-11 7.94x10-12 + -8 -8 -8 -8 -8 -8 -8 -9 -10 -11 Bi(OH)2 5.13x10 5.13x10 5.13x10 5.13x10 5.13x10 5.13x10 5.13x10 2.92x10 2.92x10 2.92x10 0 -13 -12 -11 -10 -9 -8 -7 -7 -7 -7 Bi(OH)3 6.31x10 6.31x10 6.31x10 6.31x10 6.31x10 6.31x10 6.31x10 3.59x10 3.59x10 3.59x10 - -13 -12 -11 Bi(OH)4 4.52x10 4.52x10 4.52x10 6+ Bi6(OH)12 7+ Bi9(OH)20 6+ Bi9(OH)21 BiCl2+ 2.57x10-06 2.57x10-08 2.57x10-10 2.57x10-12 + -09 -11 -13 BiCl2 3.24x10 3.24x10 3.24x10 o -11 -13 BiCl3 2.57x10 2.57x10 - BiCl4 2- BiCl5 3- BiCl6 Bi3+ 1.02x10-4 1.02x10-6 1.02x10-8 1.02x10-10 1.02x10-12 Σ 1.13x10-4 1.89x10-6 1.41x10-7 6.00x10-8 5.84x10-8 1.14x10-7 6.82x10-7 3.62x10-7 3.59x10-7 3.59x10-7 ______

118 Here then is the chemical rationale for bismuth’s geochemically immobile nature in the weathering environment. It explains the differential leaching of Mo

(more widely dispersed) in the Kingsgate deposits, as evidenced by numerous field observations of secondary Bi mineralisation in matrix that bears the casts of molybdenite “books” that have been completely removed during weathering. Further, the simple model outlined above explains the persistence of secondary Bi minerals in the highly weathered gossans of Cobar-style ores (Leverett et al., 2003, 2004,

2005a,b). The model provides the confidence that Bi can be successfully used as a pathfinder element in geochemical exploration when it is present in significant amounts in primary ores. Cobar-style mineralisation is known to bear considerable amounts of Bi (Stegman and Reynolds, 2005). Refractory elements such as Sn in these deposits have been suggested as being useful exploration guides (Leverett et al., 2004); Bi may also be useful, especially in Au-poor deposits such as Elura, to the

North of Cobar. Stable isotope measurements of some ground waters in the region

(Leverett et al., 2003, 2004) indicate that they are quite old and serve well as proxies for those that had an input to the oxidised zones, despite a very long weathering history (Pillans et al., 1999).

5.6.3 Exploration implications and previous exploration campaigns in the

Kingsgate region

Carpentaria Exploration Company PL carried out a detailed exploration program at Kingsgate in the late 1960s (Simpson, 1967). Mapping was completed over an area of approximately 150 acres and a program of drilling focussed on two sites, the so-called “southern group” (including the Old 45, Monkey and Wet Shaft pipes), and the so-called “northern group” (including the Wolfram, Mt Morgan and

119 25 Group pipes). Some 67 vertical percussion holes (total 5,655 feet) were drilled to depths of 195 feet in the southern group; only 12 holes were completed in the northern group area before “drilling was suspended because of low results.” No details were provided concerning analytical procedures for Mo and Bi. The lowest value recorded for Bi from these holes (10 feet composites) was 0.001% (10 ppm), although a few sections were recorded as <0.003% (<30 ppm). The apparent limit of detection for Mo was 0.005% (50 ppm). Results of the program were not encouraging in terms of establishing any large tonnage, low grade Mo-Bi resource and the project was abandoned.

AOG Minerals PL later developed a geochemical exploration strategy for an area covering some 861 square miles and including the Kingsgate mineral field (EL

208), as outlined by MacDuff and Snow (1971). Work undertaken included stream sediment and soil sample analyses for (inter alia) Bi, Mo and W, and covered known mineral occurrences and 80 miles of granite contact with metamorphic rocks. The latter regional program was completed shortly thereafter (MacDuff and Zerwick,

1971a). A number of features of the reported work are noteworthy in the light of the distribution of Bi outlined above, and the novel approach to understanding the extent of Bi dispersion in the supergene environment that has been developed. It is noteworthy that Mo and Bi were determined using AAS techniques. The limit of detection for Mo was 0.25 ppm and that for Bi was 5 ppm. Given the normal distribution of Bi in rocks and soils, it is concluded that the analytical method chosen was inappropriate for the task at hand. In effect, all of the results accumulated by

AOG fall into two categories, anomalous (>5 ppm Bi), and either anomalous or not

(<5 ppm Bi). Indeed, it was explicitly stated that, as far as the stream sediment survey was concerned, “anomaly levels for the various elements were arbitrarily

120 selected” and that “the results of the survey were very arbitrarily interpreted”

(MacDuff and Snow, 1971). The sole conclusions that can be drawn from the Bi analyses are that the area is anomalous in Bi and that this includes areas of known

Bi-Mo mineralisation. It is however only fair to note that the authors highlighted the fact that an analytically sensitive technique for Bi was lacking and that background and anomaly levels remained to be determined. A soil sampling orientation survey at

Kingsgate (20 samples) returned what can now be seen as anomalous Bi levels in every case, ranging from 15 to 125 ppm. Of these, 16 samples returned Mo values ranging from 1 to 13 ppm Mo and 4 samples <1 ppm Mo.

Other areas of potential interest in the region were treated in a similar fashion. An orientation soil survey over known mineralisation at Mt Mundy, about 2 km N of Kingsgate, gave A horizon Mo and Bi values of 1-10 and 8-20 ppm, respectively; B horizon values were 1-22 and 8-24 ppm, respectively, for 14 samples

(MacDuff and Snow, 1971). The Upper Pretty Valley site is about 3 km S of

Kingsgate. Soil anomalies can be viewed in the same way as those above. Of the 79 samples analysed, 73 returned Bi values of 5-20 ppm and 6 samples <5 ppm. Mo values were <0.25 ppm in 13 samples, with the remainder containing 0.25-3.25 ppm

(MacDuff and Zerwick, 1971a). Maurer’s pipe (Yarrow Creek deposit) in Portion 21,

Parish Yarrow Creek, County Gough, was also investigated. The deposit lies to the N of the Upper Pretty Valley site. Of 80 soil samples, 76 had ≥5 ppm Bi and 4 were below the 5 ppm detection limit. Later soil sampling at Maurer’s and over an area between it and Upper Pretty Valley (North Yarrow Creek prospect) gave Bi values of up to 30 and 15 ppm, respectively; Mo values reached 3.75 and 65 ppm, respectively.

However, while these results are now considered to be highly anomalous, it was

121 concluded that neither area warranted any further exploration at the time (MacDuff and Zerwick, 1971b; 1972).

A final comment on the analytical method used for Bi in these prior investigations is warranted. Its accuracy and precision are unknown. Nevertheless, it is re-emphasised that the results >5 ppm reported by Carpentaria and AOG are anomalous. The <5 ppm values represent anything from background to anomalous levels and remain undifferentiated. Because of the very low mobility of Bi in the supergene environment and its low background levels in general, it is an excellent element for geochemical exploration in its own right, and as a pathfinder for deposits with accessory Bi grades. Modern analytical methods are sufficiently accurate at low levels to properly exploit the use of Bi in geochemical exploration. On the basis of Bi geochemistry alone, it is thus concluded that the areas explored by Carpentaria and

AOG remain highly prospective. This conclusion applies to any number of exploration programs carried out in the past with the same kinds of analytical constraints and the model developed above requires that the results be re- evaluated.

Normal AAS is not a very useful analytical method for the determination of

Bi at low levels and this is important given the data above concerning the distribution of the element in rocks soils and natural waters. Modern ICP-OES or ICP-MS and other methods are both accurate and precise to much lower levels (Gholivand and

Romiani, 2006; Hinds et al., 1997) and hydride generation methods have greatly increased the sensitivity of Bi determinations using AAS (Campbell, 1992).

122

APPENDIX

144 Table A.1 Concentrations and activity coefficients of ionic species from COMICS outputs for lavendulan dissolution. Sample 1 2 3 4 5 6 7 pH 4.5105 4.5215 4.5245 4.525 4.5275 4.5255 4.5300 [H+] 3.087x10-5 3.010x10-5 2.989x10-5 2.986x10-5 2.968x10-5 2.982x10-5 2.951x10-5 3- -12 -12 -12 -12 -12 -12 -12 [AsO4 ] 1.081x10 1.103x10 1.125x10 1.135x10 1.145x10 1.128x10 1.112x10 [Cl-] 1.011x10-1 1.011x10-1 1.011x10-1 1.011x10-1 1.011x10-1 1.011x10-1 1.011x10-1 [Na+] 1.001x10-1 1.001x10-1 1.001x10-1 1.001x10-1 1.001x10-1 1.001x10-1 1.001x10-1 [Ca2+] 1.268x10-4 1.242x10-4 1.216x10-4 1.227x10-4 1.238x10-4 1.219x10-4 1.199x10-4 [Cu2+] 5.372x10-4 5.264x10-4 5.156x10-4 5.189x10-4 5.222x10-4 5.157x10-4 5.092x10-4 [CuOH+] 1.662x10-7 1.651x10-7 1.636x10-7 1.652x10-7 1.669x10-7 1.646x10-7 1.629x10-7 [CaOH+] 3.923x10-13 3.895x10-13 3.858x10-13 3.907x10-13 3.956x10-13 3.889x10-13 3.836x10-13 2- -5 -5 -5 -5 -5 -5 -5 [HAsO4 ] 2.973x10 2.992x10 3.018x10 3.034x10 3.050x10 3.009x10 2.958x10 - -4 -4 -4 -4 -4 -4 -4 [H2AsO4 ] 4.100x10 4.069x10 4.057x10 4.065x10 4.072x10 4.022x10 3.944x10 0 -6 -6 -6 -6 -6 -6 -6 [H3AsO4 ] 1.747x10 1.710x10 1.686x10 1.683x10 1.680x10 1.661x10 1.625x10 0 -7 -7 -7 -7 -7 -7 -7 [CaHAsO4 ] 3.685x10 3.631x10 3.586x10 3.638x10 3.690x10 3.584x10 3.466x10 + -7 -7 -7 -7 -7 -7 -7 [CaH2AsO4 ] 7.869x10 7.649x10 7.467x10 7.549x10 7.630x10 7.419x10 7.159x10 [CuCl+] 5.068x10-5 4.966x10-5 4.864x10-5 4.895x10-5 4.926x10-5 4.864x10-5 4.803x10-5 0 -5 -5 -5 -5 -5 -5 -5 [CuHAsO4 ] 4.299x10 4.239x10 4.189x10 4.238x10 4.287x10 4.177x10 4.053x10 + -6 -6 -6 -6 -6 -6 -6 [CuH2AsO4 ] 7.293x10 7.093x10 6.928x10 6.985x10 7.042x10 6.868x10 6.649x10 I 1.020x10-1 1.020x10-1 1.020x10-1 1.020x10-1 1.020x10-1 1.020x10-1 1.020x10-1 log γ 1+/- -0.108 -0.108 -0.108 -0.108 -0.108 -0.108 -0.108 log γ 2+/- -0.430 -0.430 -0.430 -0.430 -0.430 -0.430 -0.430 log γ 3+/- -0.968 -0.968 -0.968 -0.968 -0.968 -0.968 -0.968

145 Table A.2. Observed and calculated structure factors for gillardite.

h k l 10Fo 10Fc 10s h k l 10Fo 10Fc 10s h k l 10Fo 10Fc 10s h k l 10Fo 10Fc 10s h k l 10Fo 10Fc 10s

-1 2 0 593 574 1 0 9 3 642 646 3 -2 3 7 1677 1675 3 -2 9 10 155 153 1 -6 10 14 611 601 7

0 3 0 164 170 1 -8 10 3 101 93 3 -4 4 7 653 656 1 -7 10 10 160 151 3 0 0 15 1248 1275 11

-2 4 0 3205 3212 7 -5 10 3 598 605 1 -1 4 7 1077 1065 2 -4 10 10 1056 1056 3 -1 2 15 418 412 1

-1 5 0 435 429 1 -2 10 3 348 346 1 -3 5 7 1049 1046 2 -1 10 10 142 146 6 -3 3 15 533 532 3

-3 6 0 746 741 2 -10 11 3 461 450 6 0 5 7 1326 1324 3 -6 11 10 285 282 3 0 3 15 394 387 3

0 6 0 1770 1760 4 -7 11 3 629 629 2 -5 6 7 789 786 1 0 1 11 792 787 2 -2 4 15 937 935 3

-2 7 0 227 225 1 -4 11 3 528 527 2 -2 6 7 554 550 1 -2 2 11 1515 1520 5 -4 5 15 273 270 1

-4 8 0 1490 1492 4 -1 11 3 600 601 9 -7 7 7 691 684 2 -1 3 11 599 598 1 -1 5 15 324 325 1

-1 8 0 423 423 1 -6 12 3 232 226 4 -4 7 7 959 957 2 -3 4 11 401 395 1 -6 6 15 641 646 5

-3 9 0 192 194 1 -1 1 4 478 472 2 -1 7 7 778 780 1 0 4 11 1081 1078 3 -3 6 15 131 123 2

0 9 0 318 316 2 0 2 4 3441 3434 9 -6 8 7 213 205 1 -5 5 11 489 492 2 0 6 15 550 553 3

-5 10 0 442 435 2 -2 3 4 85 71 1 -3 8 7 539 544 1 -2 5 11 596 594 1 -5 7 15 342 347 2

-2 10 0 1023 1023 2 -4 4 4 2261 2269 5 0 8 7 359 362 2 -4 6 11 799 802 2 -2 7 15 289 287 2

-4 11 0 205 201 2 -1 4 4 144 132 1 -8 9 7 549 543 2 -1 6 11 212 214 1 -7 8 15 170 166 3

-1 11 0 122 116 6 -3 5 4 315 313 1 -5 9 7 717 714 2 -6 7 11 307 301 1 -4 8 15 532 533 2

-6 12 0 948 952 9 0 5 4 48 34 1 -2 9 7 637 644 1 -3 7 11 400 400 1 -1 8 15 132 136 2

-1 1 1 1650 1636 6 -5 6 4 239 234 1 -10 10 7 144 133 11 0 7 11 353 363 2 -6 9 15 300 305 3

146 0 2 1 1614 1630 4 -2 6 4 1588 1577 3 -7 10 7 458 460 2 -8 8 11 471 467 3 -3 9 15 236 238 3

-2 3 1 589 615 1 -7 7 4 88 73 2 -4 10 7 296 299 1 -5 8 11 112 105 2 -1 1 16 277 272 2

-4 4 1 1419 1425 3 -4 7 4 38 11 2 -1 10 7 493 494 2 -2 8 11 584 587 1 0 2 16 1388 1383 7

-1 4 1 1070 1068 1 -1 7 4 77 70 1 -6 11 7 498 494 2 -7 9 11 249 245 2 -2 3 16 429 425 2

-3 5 1 1169 1156 2 -6 8 4 1194 1190 2 -3 11 7 631 621 3 -4 9 11 334 338 1 -4 4 16 1338 1338 6

0 5 1 345 339 1 -3 8 4 272 266 1 0 1 8 483 501 1 -1 9 11 274 273 2 -1 4 16 206 206 2

-5 6 1 665 661 1 0 8 4 845 849 2 -2 2 8 1919 1940 6 -9 10 11 211 221 15 -3 5 16 176 173 2

-2 6 1 915 912 1 -8 9 4 59 41 3 -1 3 8 792 802 1 -6 10 11 485 485 2 0 5 16 425 428 2

-7 7 1 634 633 2 -5 9 4 37 14 4 -3 4 8 308 312 1 -3 10 11 127 130 3 -5 6 16 171 168 2

-4 7 1 515 509 1 -2 9 4 69 52 2 0 4 8 1255 1248 3 -5 11 11 298 299 9 -2 6 16 1121 1121 4

-1 7 1 525 520 1 -10 10 4 788 784 21 -5 5 8 694 701 2 0 0 12 1576 1571 10 -7 7 16 165 159 4

-6 8 1 910 911 2 -7 10 4 148 141 2 -2 5 8 259 252 1 -1 2 12 182 185 1 -4 7 16 255 254 2

-3 8 1 534 538 1 -4 10 4 867 873 2 -4 6 8 1116 1112 2 -3 3 12 435 444 1 -1 7 16 213 217 2

0 8 1 436 440 1 -1 10 4 71 63 4 -1 6 8 281 276 1 0 3 12 100 98 1 -6 8 16 1087 1084 4

-8 9 1 491 490 1 -9 11 4 127 121 5 -6 7 8 321 320 1 -2 4 12 1281 1273 3 -3 8 16 103 101 3

-5 9 1 397 392 1 -6 11 4 109 109 3 -3 7 8 424 418 1 -4 5 12 68 54 2 0 8 16 777 790 5

-2 9 1 365 369 1 -3 11 4 33 31 12 0 7 8 203 198 1 -1 5 12 248 241 1 -5 9 16 236 239 5

-10 10 1 609 600 5 -5 12 4 95 64 12 -8 8 8 810 809 4 -6 6 12 1098 1094 5 -2 9 16 175 166 14

-7 10 1 385 386 1 0 1 5 194 233 1 -5 8 8 175 174 1 -3 6 12 142 134 1 0 1 17 652 650 4

-4 10 1 503 506 1 -2 2 5 1539 1579 5 -2 8 8 594 604 1 0 6 12 771 783 3 -2 2 17 328 329 3

147 -1 10 1 314 313 2 -1 3 5 777 778 1 -7 9 8 250 247 2 -5 7 12 220 220 1 -1 3 17 495 488 2

-9 11 1 307 307 3 -3 4 5 562 559 1 -4 9 8 314 314 1 -2 7 12 46 12 4 -3 4 17 672 667 2

-6 11 1 456 455 2 0 4 5 1283 1281 3 -1 9 8 155 148 2 -7 8 12 143 140 2 0 4 17 427 425 3

-3 11 1 174 164 2 -5 5 5 533 537 1 -9 10 8 212 213 4 -4 8 12 830 840 2 -5 5 17 318 315 2

-5 12 1 334 338 4 -2 5 5 129 120 1 -6 10 8 671 669 2 -1 8 12 83 72 2 -2 5 17 594 599 2

0 1 2 321 340 1 -4 6 5 1306 1306 2 -3 10 8 157 155 2 -9 9 12 69 72 14 -4 6 17 379 373 2

-2 2 2 1402 1429 3 -1 6 5 504 506 1 -8 11 8 342 344 7 -6 9 12 190 190 2 -1 6 17 566 567 2

-1 3 2 148 170 1 -6 7 5 356 348 1 -5 11 8 115 105 4 -3 9 12 37 2 7 -6 7 17 472 477 3

-3 4 2 634 631 1 -3 7 5 320 315 1 -2 11 8 122 131 19 0 9 12 57 52 13 -3 7 17 372 375 2

0 4 2 1623 1624 4 0 7 5 146 149 1 0 0 9 491 512 3 -8 10 12 773 768 7 0 7 17 484 498 3

-5 5 2 23 24 4 -8 8 5 1003 1009 5 -1 2 9 975 974 2 -5 10 12 97 94 4 -5 8 17 566 566 3

-2 5 2 266 264 1 -5 8 5 444 443 1 -3 3 9 849 850 2 -2 10 12 521 530 4 -2 8 17 436 433 6

-4 6 2 1392 1376 2 -2 8 5 811 816 1 0 3 9 627 614 2 -1 1 13 1057 1047 4 0 0 18 957 962 12

-1 6 2 522 526 1 -7 9 5 245 241 1 -2 4 9 706 706 1 0 2 13 120 111 2 -1 2 18 317 319 2

-6 7 2 303 302 1 -4 9 5 230 231 1 -4 5 9 747 735 1 -2 3 13 1075 1058 3 -3 3 18 204 206 3

-3 7 2 172 169 1 -1 9 5 140 132 1 -1 5 9 790 792 1 -4 4 13 240 233 2 0 3 18 494 487 3

0 7 2 246 249 1 -9 10 5 254 247 3 -6 6 9 744 746 3 -1 4 13 1095 1088 2 -2 4 18 763 762 3

-8 8 2 896 896 3 -6 10 5 766 770 2 -3 6 9 928 932 2 -3 5 13 784 785 2 -4 5 18 305 303 2

-5 8 2 521 531 1 -3 10 5 299 303 1 0 6 9 600 602 2 0 5 13 815 819 3 -1 5 18 191 184 2

-2 8 2 1099 1104 2 0 10 5 515 513 4 -5 7 9 535 536 1 -5 6 13 978 985 3 -6 6 18 463 466 4

148 -7 9 2 189 193 1 -8 11 5 270 267 3 -2 7 9 476 484 1 -2 6 13 296 290 1 -3 6 18 129 127 3

-4 9 2 153 148 1 -5 11 5 63 57 5 -7 8 9 634 630 2 -7 7 13 609 615 3 0 6 18 635 634 4

-1 9 2 213 207 1 -2 11 5 253 253 3 -4 8 9 595 596 1 -4 7 13 750 753 2 -5 7 18 166 167 3

-9 10 2 189 187 2 0 0 6 2309 2328 18 -1 8 9 582 590 1 -1 7 13 732 736 2 -2 7 18 335 326 2

-6 10 2 775 774 2 -1 2 6 406 398 1 -9 9 9 475 461 6 -6 8 13 273 268 2 -7 8 18 106 102 24

-3 10 2 325 325 1 -3 3 6 856 836 2 -6 9 9 471 468 2 -3 8 13 887 893 2 -4 8 18 510 504 4

0 10 2 746 736 7 0 3 6 114 116 1 -3 9 9 359 358 1 0 8 13 303 301 2 -1 1 19 750 753 5

-8 11 2 49 38 8 -2 4 6 2126 2121 4 0 9 9 465 480 3 -8 9 13 556 565 3 0 2 19 427 429 4

-5 11 2 122 116 2 -4 5 6 93 94 1 -8 10 9 489 489 4 -5 9 13 540 542 2 -2 3 19 564 566 3

-2 11 2 234 235 2 -1 5 6 343 335 1 -5 10 9 591 595 2 -2 9 13 622 632 2 -4 4 19 368 362 3

-7 12 2 214 215 4 -6 6 6 1474 1468 4 -2 10 9 391 397 2 -7 10 13 657 658 4 -1 4 19 566 570 2

-4 12 2 598 581 9 -3 6 6 46 17 2 -7 11 9 333 330 3 -4 10 13 226 222 3 -3 5 19 689 695 3

0 0 3 1312 1349 7 0 6 6 1749 1752 4 -4 11 9 400 408 3 0 1 14 242 249 2 0 5 19 465 469 3

-1 2 3 2159 2132 4 -5 7 6 390 384 1 -1 1 10 673 667 2 -2 2 14 1353 1352 5 -5 6 19 435 436 3

-3 3 3 1301 1309 3 -2 7 6 131 125 1 0 2 10 2217 2208 7 -1 3 14 71 49 3 -2 6 19 221 223 2

0 3 3 2404 2378 6 -7 8 6 84 71 2 -2 3 10 190 190 1 -3 4 14 137 130 1 -7 7 19 477 494 12

-2 4 3 786 797 1 -4 8 6 1391 1393 3 -4 4 10 1787 1773 6 0 4 14 1207 1203 5 -4 7 19 485 489 4

-4 5 3 1485 1475 2 -1 8 6 56 38 2 -1 4 10 404 401 1 -5 5 14 116 108 3 -1 7 19 425 437 3

-1 5 3 1166 1164 2 -9 9 6 116 100 4 -3 5 10 638 637 1 -2 5 14 315 309 1 0 1 20 301 296 5

-6 6 3 195 188 1 -6 9 6 243 244 1 0 5 10 92 89 2 -4 6 14 904 906 3 -2 2 20 975 972 7

149 -3 6 3 1071 1071 1 -3 9 6 138 137 1 -5 6 10 227 225 1 -1 6 14 47 22 4 -1 3 20 186 189 3

0 6 3 590 590 1 0 9 6 37 21 9 -2 6 10 1698 1693 4 -6 7 14 59 54 4 -3 4 20 156 149 3

-5 7 3 891 888 1 -8 10 6 897 893 3 -7 7 10 397 397 2 -3 7 14 41 21 5 0 4 20 941 929 9

-2 7 3 1204 1203 2 -5 10 6 45 11 5 -4 7 10 226 228 1 0 7 14 194 196 2 -5 5 20 179 187 4

-7 8 3 729 732 1 -2 10 6 1086 1093 3 -1 7 10 253 257 1 -8 8 14 541 545 4 -2 5 20 282 279 2

-4 8 3 318 315 1 -7 11 6 84 80 5 -6 8 10 1124 1119 3 -5 8 14 28 15 11 -4 6 20 954 948 4

-1 8 3 785 790 1 -4 11 6 136 138 3 -3 8 10 192 190 1 -2 8 14 874 879 3 -1 6 20 78 75 6

-9 9 3 570 569 3 -6 12 6 743 760 16 0 8 10 1293 1302 4 -7 9 14 7 5 7 -6 7 20 87 94 30

-6 9 3 703 698 2 -1 1 7 1634 1651 5 -8 9 10 277 278 2 -4 9 14 80 65 4 -3 7 20 187 194 5

-3 9 3 872 878 2 0 2 7 1276 1278 3 -5 9 10 234 238 1 -1 9 14 115 106 5 0 0 21 587 591 8

-1 2 21 207 206 3 -4 5 21 266 267 3 0 2 22 944 946 7 -3 5 22 33 6 32 -3 4 23 524 526 4

-3 3 21 70 51 7 -1 5 21 131 129 4 -2 3 22 64 59 7 0 1 23 588 570 8 0 4 23 106 102 14

0 3 21 321 321 4 -3 6 21 245 246 4 -4 4 22 760 764 6 -2 2 23 173 166 7 -1 2 24 81 84 11

-2 4 21 582 579 5 -1 1 22 34 25 30 -1 4 22 79 66 6 -1 3 23 667 665 7

150 Table A.3. Crystallographic Information File (CIF) for gillardite. data_global _chemical_name 'Gillardite' loop_ _publ_author_name 'Clissold M E' 'Leverett P' 'Williams P A' 'Hibbs D E' 'Nickel E H' _journal_name_full "The Canadian Mineralogist" _journal_volume 45 _journal_year 2007 _journal_page_first 317 _journal_page_last 320 _publ_section_title ; The structure of gillardite, the Ni-analogue of herbertsmithite, from Widgiemooltha, Western Australia Locality: 132N deposit, Widgiemooltha, Australia ; _chemical_formula_sum 'Cu3.081 Ni.903 Co.012 Fe.004 Cl2 O6 H6' _cell_length_a 6.8364 _cell_length_b 6.8364 _cell_length_c 13.8459 _cell_angle_alpha 90 _cell_angle_beta 90 _cell_angle_gamma 120 _cell_volume 560.411 _symmetry_space_group_name_H-M 'R -3 m' loop_ _symmetry_equiv_pos_as_xyz 'x,y,z' '2/3+x,1/3+y,1/3+z' '1/3+x,2/3+y,2/3+z' 'x,x-y,z' '2/3+x,1/3+x-y,1/3+z' '1/3+x,2/3+x-y,2/3+z' 'y,x,-z' '2/3+y,1/3+x,1/3-z' '1/3+y,2/3+x,2/3-z' '-x+y,y,z' '2/3-x+y,1/3+y,1/3+z' '1/3-x+y,2/3+y,2/3+z' '-x,-x+y,-z' '2/3-x,1/3-x+y,1/3-z' '1/3-x,2/3-x+y,2/3-z' '-y,-x,z' '2/3-y,1/3-x,1/3+z' '1/3-y,2/3-x,2/3+z' 'x-y,-y,-z' '2/3+x-y,1/3-y,1/3-z' '1/3+x-y,2/3-y,2/3-z' 'y,-x+y,-z' '2/3+y,1/3-x+y,1/3-z' '1/3+y,2/3-x+y,2/3-z' '-x+y,-x,z' '2/3-x+y,1/3-x,1/3+z' '1/3-x+y,2/3-x,2/3+z'

151 '-x,-y,-z' '2/3-x,1/3-y,1/3-z' '1/3-x,2/3-y,2/3-z' '-y,x-y,z' '2/3-y,1/3+x-y,1/3+z' '1/3-y,2/3+x-y,2/3+z' 'x-y,x,-z' '2/3+x-y,1/3+x,1/3-z' '1/3+x-y,2/3+x,2/3-z' loop_ _atom_site_label _atom_site_fract_x _atom_site_fract_y _atom_site_fract_z _atom_site_occupancy _atom_site_Uiso_or_equiv Cu2 0.50000 0.00000 0.00000 1.00000 0.00540 Ni1 0.00000 0.00000 0.50000 0.90300 0.00430 Cu1 0.00000 0.00000 0.50000 0.08100 0.00430 Co1 0.00000 0.00000 0.50000 0.01200 0.00430 Fe1 0.00000 0.00000 0.50000 0.00400 0.00430 Cl 0.00000 0.00000 0.19330 1.00000 0.00730 O 0.20700 -0.20700 0.06240 1.00000 0.00730 H 0.14400 -0.14400 0.08580 1.00000 0.02200 loop_ _atom_site_aniso_label _atom_site_aniso_U_11 _atom_site_aniso_U_22 _atom_site_aniso_U_33 _atom_site_aniso_U_12 _atom_site_aniso_U_13 _atom_site_aniso_U_23 Cu2 0.00530 0.00490 0.00580 0.00245 0.00055 0.00110 Ni1 0.00490 0.00490 0.00310 0.00245 0.00000 0.00000 Cu1 0.00490 0.00490 0.00310 0.00245 0.00000 0.00000 Co1 0.00490 0.00490 0.00310 0.00245 0.00000 0.00000 Fe1 0.00490 0.00490 0.00310 0.00245 0.00000 0.00000 Cl 0.00800 0.00800 0.00590 0.00400 0.00000 0.00000 O 0.00670 0.00670 0.00870 0.00340 0.00110 -0.00110

152 REFERENCES

Abdel-Aal, E.A., Rashad, M.M. and El-Shall, H. (2004) Crystallisation of calcium

sulfate dihydrate at different supersaturation ratios and different free sulfate

concentrations. Crystal Research and Technology, 39, 313-321.

Ahrens, L.H. and Erlank, A.J. (1978) Bismuth. In: Wedepohl, K.H. (Ed.) Handbook

of Geochemistry. Springer-Verlag, Berlin, Volume II, Sections 83-D-1 to

83-O-1.

Andrews, E.C. (1906) Molybdenum. New South Wales Department of Mines,

Geological Survey, Mineral Resources Series, No. 11.

Andrews, E.C. (1916) The Molybdenum Industry in New South Wales. New South

Wales Department of Mines, Geological Survey, Mineral Resources Series,

No. 24.

Angio, E.E. and Long, D.T. (Eds) (1979) Geochemistry of Bismuth. Dowden,

Hutchinson and Ross, Inc., Stroudsburg, PA, USA.

Anthony, J.W., Bideaux, R.A., Bladh, K.W. and Nichols, M.C. (1990) Handbook of

Mineralogy Volume 1: Elements, Sulfides, Sulfosalts. Mineral Data

Publishing, Tucson, Arizona.

Anthony, J.W., Bideaux, R.A., Bladh, K.W. and Nichols, M.C. (1995) Handbook of

Mineralogy Volume 2: Silica, Silicates. Mineral Data publishing, Tucson,

Arizona.

123 Anthony, J.W., Bideaux, R.A., Bladh, K.W. and Nichols, M.C. (1997) Handbook of

Mineralogy Volume 3: Halides, Hydroxides, Oxides. Mineral Data

publishing, Tucson, Arizona.

Anthony, J.W., Bideaux, R.A., Bladh, K.W. and Nichols, M.C. (2000) Handbook of

Mineralogy Volume 4: Arsenates, Phosphates, Vanadates. Mineral Data

Publishing, Tucson, Arizona.

Anthony, J.W., Bideaux, R.A., Bladh, K.W. and Nichols, M.C. (2003) Handbook of

Mineralogy Volume 5: Borates, Carbonates, . Mineral Data

Publishing, Tucson, Arizona.

Appelo, C.A.J. and Postma, D. (1993) Geochemistry, Groundwater and Pollution.

A.A. Balkema, Rotterdam.

Arai, Y. and Sparks, D.L. (2001) ATR-FTIR spectroscopic investigation of

phosphate adsorption mechanisms at the ferrihydrite-water interface.

Journal of Colloid and Interface Science, 241, 317-326.

Arundell, M.C. (2004) Northparkes Cu-Au mines, central NSW. In: Butt, C.R.M,

Cornelius, M., Scott, K.M. and Robertson, I.D.M. (Eds) Regolith Expression

of Australian Ore Systems. CRC LEME, Perth.

Baes, C.F. Jr and Mesmer, R.E. (1976) The Hydrolysis of Cations. Plenum Press,

New York.

124 Baker, T., Pollard, P.J., Mustard, R., Mark, G. and Graham, J.L. (2005) A

comparison of granite-related tin, tungsten and gold–bismuth deposits:

implications for exploration. Society of Exploration Geologists Newsletter,

61, 5–17.

Barreca, D., Morazzoni, F., Rizzi, G.A, Scotti, R. and Tondello, E. (2001) Molecular

oxygen interaction with Bi2O3: a spectroscopic and spectromagnetic

investigation. Physical Chemistry and Chemical Physics, 3, 1743-1749.

Birch, W.D. (1990) Minerals from the Kintore and Block 14 open cuts, Broken Hill,

New South Wales; a review of recent discoveries including tsumebite,

kipushite and otavite. Australian Mineralogist, 5, 125-141.

Birch, W.D. (1999) The Minerals. In: Birch, W.D. (Ed.) The Minerals of Broken

Hill, Broken Hill City Council and Museum Victoria, Broken Hill,

Australia, 88-262.

Birch, W.D., Pring, A., McBriar, E.M. Gatehouse, B.M. and McCammon, C.A.

3+ (1998) Bamfordite, Fe Mo2O6(OH)3·H2O, a new hydrated iron

molybdenum oxyhydroxide from Queensland, Australia: description and

crystal chemistry. American Mineralogist, 83, 172-177.

Blount, C.W. (1977) Barite solubilities and thermodynamic quantities up to 300oC

and 1400 bars. American Mineralogist, 62, 942-957.

Booker, F.W. (1943) Quartz crystal at Comstock. In: Mulholland, C. St J. Geological

Reports 1939-1945. New South Wales Department of Mines, Sydney.

125 Braithwaite, R.S.W., Mereiter, K., Paar, W.H. and Clark, A.M. (2004)

Herbertsmithite, Cu3Zn(OH)6Cl2, a new species, and the definition of

paratacamite. Mineralogical Magazine, 68, 527-539.

Brandenstein, M., Janda., I. and Schroll, E. (1960) Seltene elemente in

österreichischen kohlen- und bitumengesteinen. Tschermaks Mineralogische

und Petrographische Mittelilungen, 7, 260-269.

Breithaupt, A. (1837) Bestimmung neuer mineralien. Journal für Praktische Chemie,

10, 505-506.

Brown, R.E. (1995) Exploration Data Package for the Glen Innes 1:100000 Sheet

Area. Geological Survey of New South Wales Report, GS1995/231,

Volumes 1-2.

Callaghan, T. (2001) Geology and host-rock alteration of the Henty and Mount Julia

gold deposits, western Tasmania. Economic Geology, 96, 1073-1088.

Campbell, A.D. (1992) A critical survey of hydride generation techniques in atomic

spectroscopy. Pure and Applied Chemistry, 64, 227-244.

Chapman, J.R., Sharpe, J.L. and Williams, P.A. (2005) The copper deposits at

Girilambone, New South Wales. Australian Journal of Mineralogy, 11, 91-

99.

Chiappero, P.J. and Sarp, H. (1995) Zdenekite, NaPbCu5(AsO4)4Cl·5H2O, a new

mineral from the Cap Garonne mine, Var, France. European Journal of

Mineralogy, 7, 553-557.

126 Clissold, M.E., Leverett, P. and Williams, P.A. (2003) Gaspéite-magnesite solid

solutions and their significance. CRC LEME Regional Regolith Symposia,

78-79.

Clissold, M.E., Leverett, P., Williams, P.A., Hibbs, D.E. and Nickel, E.H. (2007) The

structure of gillardite, Cu3NiCl2(OH)6, from Widgiemooltha, Western

Australia: the Ni-analogue of herbertsmithite. The Canadian Mineralogist,

45, 317-320.

Colchester, D.M., Leverett, P., Clissold, M.E., Williams, P.A., Hibbs, D.E. and

Nickel, E.H. (2007) Gillardite, Cu3NiCl2(OH)6, a new mineral from the 132

North deposit, Widgiemooltha, Western Australia. Australian Journal of

Mineralogy, 13, 21-24.

Collins, P., Hooper, B. and Cornelius, M. (2004) Whim Creek Cu-Zn-Pb deposit,

Pilbara, WA. In: Butt, C.R.M., Cornelius, M., Scott, K.M. and Robertson,

I.D.M. (Eds) Regolith Expression of Australian Ore Systems. CRC LEME,

Perth, 1-3.

Cook, R.B. (1978) Famous mineral localities: Chuquicamata, Chile. The

Mineralogical Record, 9, 321-333.

Crane, M.J., Sharpe, J.L. and Williams, P.A. (1998) The mineralogy of the oxidized

zones of the E22 and E27 ore bodies at Northparkes, New South Wales.

Australian Journal of Mineralogy, 4, 1-8.

Crane, M.J., Sharpe, J.L. and Williams, P.A. (2001) Formation of chrysocolla and

secondary copper phosphates in the highly weathered supergene zones of

some Australian deposits. Records of the Australian Museum, 53, 49-56.

127 de Wolff, P.M. (1953) Crystal structure of Co2(OH)3Cl. Acta Crystallographica, 6,

359-360.

Dolling, P.J., Moody, P., Noble, A., Helyar, K., Hughes, B., Reuter, D. and Sparrow,

L. (2001) Soil Acidity and Acidification. Final report to National Land and

Water Resources Audit for Project 5.4C.

Elvy, S.B. (1998) Geochemical studies of base and noble metal compounds. PhD

thesis, University of Western Sydney, Sydney.

Emmons, W.H. (1917) The enrichment of ore deposits. United States Geological

Survey Bulletin, 625.

Emsley, J. (1991) The Elements. Second edition, Oxford University Press, Oxford.

England, B.M. (1985) Famous mineral localities: the Kingsgate mines. The

Mineralogical Record, 16, 265-289.

Fleet, M.E. (1975) The crystal structure of paratacamite, Cu2(OH)3Cl. Acta

Crystallographica B, 31, 183-187.

Fogarty, J.M. (1998) Girilambone district copper deposits. In: Berkman, D.A. and

Mackenzie, D.H. (Eds) Geology of Australian and Papua New Guinean

Mineral Deposits, Australasian Institute of Mining and Metallurgy,

Melbourne, 593-600.

Foshag, W.F. (1924a) Freirinite: a new mineral species. American Mineralogist, 9,

30-31.

128 Foshag, W.F. (1924b) Note on lavendulan from Joachimsthal, Bohemia. American

Mineralogist, 9, 29-30.

Frondel, C. (1950) On paratacamite and some related copper chlorides.

Mineralogical Magazine, 29, 34-45.

Gaines, R.V., Skinner, H.C.W., Foord, E.E., Mason, B. and Rosenzweig, A. (1997)

Dana's New Mineralogy. Eighth edition, John Wiley and Sons, New York.

Garrels, R.M. and Christ, C.L. (1965) Solutions, Minerals, and Equilibria. Harper

and Row, New York.

Garretty, M.D. (1943) Quartz Crystal Report No. 10, Further N.S.W. Localities.

Sandy Hill, Comstock. New South Wales Department of Primary Industries

(Mineral Resources) Open File Report, No. R00025695.

Garretty, M.D. (1944a) Crystal Report No. 14, Kingsgate Crystal Field. Part I. New

South Wales Department of Primary Industries (Mineral Resources) Open

File Report, No. R00025697.

Garretty, M.D. (1944b) Crystal Report No. 14, Kingsgate Crystal Field. Part II. New

South Wales Department of Primary Industries (Mineral Resources) Open

File Report, No. R002588150.

Gholivand, M.B. and Romiani, A.A. (2006) Highly sensitive and selective

measurement of bismuth in seawater and drug with 1,2-

phenylenedioxydiacetic acid by cathodic adsorptive stripping voltammetry.

Electroanalysis, 18, 730-734.

129 Giester, G., Kolitsch, U., Leverett, P., Turner, P. and Williams, P.A. (2007) The

crystal structures of lavendulan, sampleite and a new polymorph of

sampleite. European Journal of Mineralogy, 19, 75-93.

Goldschmidt, V.M. (1970) Geochemistry. Oxford University Press, Oxford.

Goldsmith, E. (1887) On lavendulite from Chili, S. A. Proceedings of the Academy

of Natural Sciences of Philadelphia, 192-193.

Golič, L., Grauer, M. and Lazarini, F. (1982) Catena-di--hydroxo- 3-oxo-

dibismuth(III) sulfate. Acta Crystallographica, B38, 2881-2883.

Grauer, M. and Lazarini, F. (1982) Di--hydroxo-bis[aquasulfatobismuth(III)]. Acta

Crystallographica, B38, 2879-2881.

Grice, J.D., Szymanski, J.T. and Jambor, J.L. (1996) The crystal structure of

clinoatacamite, a new polymorph of Cu2(OH)3Cl. The Canadian

Mineralogist, 34, 73-78.

Guillemin, C. (1956) Contribution à la minéralogie des arséniates, phosphates et

vanadates de cuivre. Bulletin de la Société Française de Minéralogie et

Cristallographie, 79, 7-95.

Hale, M. (1981) Pathfinder applications of , antimony and bismuth in

geochemical exploration. Journal of Geochemical Exploration, 15, 307-323.

Hassan, L.Y. and Clarke, R.M. (2005) Some unusual gold and bismuth

mineralization at Mardoonganna Hill, Murchison mineral field. Annual

Review of the Geological Survey of Western Australia for 2004-2005,

Technical Papers, 83-87, and references therein.

130 Hawkes, H.E. and Webb, J.S. (1962) Geochemistry in Mineral Exploration. Harper

and Row, New York.

Heart of the Bay International Crystals, (2006)

www.heartofthebay.com.au/asu_cry.htm.

Heithersay, P.S., O'Neill, W.J., van der Helder, P., Moore, C.R. and Harbon, P.G.

(1990) Goonumbla porphyry copper district - Endeavour 26 North,

Endeavour 22 and Endeavour 27 copper-gold deposits. In: Hughes, F.E.

(Ed.) Geology of the Mineral Deposits of Australia and Papua New Guinea,

The Australasian Institute of Mining and Metallurgy, Melbourne, 1385-

1398.

Hinds, M.W. Grégoire, D.C. and Ozaki, E.A. (1997) Direct determination of volatile

elements in nickel alloys by electrothermal vaporization inductively coupled

plasma mass spectrometry. Journal of Analytical Atomic Spectrometry, 12,

131-135.

Jambor, J.L., Dutrizac, J.T., Roberts, A.C., Grice, J.D. and Szymanski, J.T. (1996)

Clinoatacamite, a new polymorph of Cu2(OH)3Cl, and its relationship to

paratacamite and "anarakite". The Canadian Mineralogist, 34, 61-72.

Kabata-Pendias, A. (2001) Trace Elements in Soils and Plants. 3rd Edition, CRC

Press, Boca Raton, Florida.

Kaye, G.W.C. and Laby, T.H. (1995) Tables of Physical and Chemical Constants.

16th Edition, Longman, London, Section 3.10.5.

131 Kleeman, A.W. and Milnes, A.R. (1973) Phosphorian lavendulan from Dome Rock

mine, South Australia. Transactions of the Royal Society of South Australia,

97, 135-137.

Kokinos, M. and Wise, W.S. (1993) The Gold Hill mine, Tooele County, Utah. The

Mineralogical Record, 24, 11-22.

Kraus, W. and Nolze, G. (1996a) PowderCell 1.8 and Windows version 1.0. Federal

Institute for Materials Research and Testing (BAM), Berlin.

Kraus, W. and Nolze, G. (1996b) PowderCell - a program for the representation and

manipulation of crystal structures and calculation of the resulting X-ray

powder patterns. Journal of Applied Crystallography, 29, 301-303.

Krause, W., Bernhardt, H.-J., Braithwaite, R.S.W., Kolitsch, U. and Pritchard, R.

(2006) Kapellasite, Cu3Zn(OH)6Cl2, a new mineral from Lavrion, Greece.

Mineralogical Magazine, 70, 331-342.

Lancia, A., Musmarra, D. and Prisciandaro, M. (1999) Measuring induction period

for calcium sulfate dihydrate precipitation. American Institute of Chemical

Engineers Journal, 45, 390-397.

Lang, J.R. and Baker, T. (2001) Intrusion-related gold systems: the present level of

understanding. Mineralium Deposita, 36, 477-489.

Langford, J.I. (1973) Least-squares refinement of cell dimensions from powder data

by Cohen's method. Journal of Applied Crystallography, 6, 190-196.

Lawrence, L.J. (1998) Molybdenite, bismuth and associated minerals. Australian

Journal of Mineralogy, 4, 81-85.

132 Lawrence, L.J. and Markham, N.L. (1962) A contribution to the study of the

molybdenite pipes of Kingsgate, New South Wales, with special reference

to ore mineralogy. Proceedings of the Australasian Institute of Mining and

Metallurgy, 203, 67-94.

Lawrence, L.J., Ramsden, A.R. and Munro-Smith, V. (1998) Maldonite and its

paragenesis at Kingsgate, New South Wales. Journal and Proceedings of

the Royal Society of New South Wales, 131, 13-18.

Leverett, P., McKinnon, A.R. and Williams, P.A. (2003) Mineralogy of the oxidised

zone of the New Cobar orebody. In: I.C. Roach (Ed.) Advances in Regolith,

CRC LEME, Canberra, 267-270.

Leverett, P., McKinnon, A.R. and Williams, P.A. (2004) A supergene exploration

model for Cobar style deposits. In: McQueen, K.G. and Scott, K.M. (Eds)

Exploration Field Workshop Cobar Region 2004, Proceedings, CRC

LEME, Perth, 46-50.

Leverett, P., McKinnon, A.R. and Williams, P.A. (2005a) Supergene geochemistry

of the Endeavor ore body, Cobar, NSW, and relationships to other deposits

in the Cobar Basin. In: I.C. Roach (Ed.) Regolith 2005 – Ten Years of CRC

LEME, CRC LEME, 191-194.

Leverett, P., McKinnon, A.R., Sharpe, J.L. and Williams, P.A. (2005b) Secondary

minerals from the central Cobar mines. Australian Journal of Mineralogy,

11, 75-82.

133 Levin, E.M. and Roth, R.S. (1964) Polymorphism of bismuth sesquioxide. I. Pure

Bi2O3. Journal of Research of the National Bureau of Standards, 68A, 189-

195.

Lovreček, B., Mekjavić, I. and Metikoš-Huković, M. (1985) Bismuth. In: Bard, A.J.,

Parsons, R. and Jordan, J. (Eds) Standard Potentials in Aqueous Solution.

International Union of Pure and Applied Chemistry and Marcel Dekker,

New York, 180-187.

Lueth, V.W. (1999), Bismuth: Element and Geochemistry. In: Fairbridge, R.W. (Ed.)

The Encyclopaedia of Geochemistry. Kluwer Academic Publishers, London,

43-44.

MacDuff, R. and Snow, A. (1971) Quarterly Report Period to 8th January 1971,

EL208, AOG Minerals PL. New South Wales Department of Primary

Industries (Mineral Resources) Open File Reports, No. R00028059.

MacDuff, R. and Zerwick, J. (1971a) EL208, Quarterly Report Period to 8th July

1971, AOG Minerals PL. New South Wales Department of Primary

Industries (Mineral Resources) Open File Reports, No. R00007895.

MacDuff, R. and Zerwick, J. (1971b) EL208, Quarterly Report Period to 8th October

1971, AOG Minerals PL. New South Wales Department of Primary

Industries (Mineral Resources) Open File Reports, No. R00007896.

MacDuff, R. and Zerwick, J. (1972) EL208, Quarterly Report Period to 8th January

1972, AOG Minerals PL. New South Wales Department of Primary

Industries (Mineral Resources) Open File Reports, No. R00007897.

134 Madrakian, T., Afkhami, A. and Esmaeili, A. (2003) Spectrophotometric

determination of bismuth in water samples after preconcentration of its

thiourea-bromide ternary complex on activated carbon. Talanta, 60, 831-

838.

Magalhães, M.C.F., Pedrosa de Jesus, J.D. and Williams, P.A. (1986) Stability

constants and formation of Cu(II) and Zn(II) phosphate minerals in the

oxidised zone of base metal orebodies. Mineralogical Magazine, 50, 33-39.

Magalhães, M.C.F., Pedrosa de Jesus, J.D. and Williams, P.A. (1988) The chemistry

of formation of some secondary arsenate minerals of Cu(II), Zn(II) and

Pb(II). Mineralogical Magazine, 52, 679-690.

Makovicky, E. and Karup-Møller, S. (1972a) Chemistry and crystallography of the

lillianite homologous series. I. General properties and definitions. Neues

Jahrbuch für Mineralogie, Abhandlung, 130, 264-287.

Makovicky, E. and Karup-Møller, S. (1972b) Chemistry and crystallography of the

lillianite homologous series. I. Definition of new minerals, eskimoite,

vikingite, ourayite and treasurite, redefinition of schirmerite and new data

on the lillianite-gustavite solid solution series. Neues Jahrbuch für

Mineralogie, Abhandlung, 131, 56-82.

Marston, R.J., Groves, D.I., Hudson, D.R. and Ross, J.R. (1981) Nickel sulfide

deposits in Western Australia: a review. Economic Geology, 76, 1330-1363.

Martell, A.E. and Smith, A.M.L. (1982) Critical Stability Constants Volume 5: First

Supplement. Plenum Press, New York.

135 McLean, A.L., Chapman, J., Sharpe, J.L. and Williams, P.A. (2004) The mineralogy

of the oxidized zone of the E26 ore body at Northparkes, New South Wales.

Australian Journal of Mineralogy, 10, 53-58.

McKinnon, A.R. (2007) A Geochemical Exploration Model for Ore Deposits in the

Cobar Basin. PhD Thesis, University of Western Sydney.

McQueen, K.G. (1981) Volcanic-associated nickel deposits from around the

Widgiemooltha Dome, Western Australia. Economic Geology, 76, 1417-

1443.

McQueen, K.G., Pillans, B.J. and Smith, M.I. (2002) Constraining the weathering

history of the Cobar region, western NSW. In: Preiss, V.P. (Ed.) Abstracts

of the 16th Australian Geological Convention, Proceedings. Geological

Society of Australia.

Melchiorre, E.B. and Enders, M.S. (2003) Stable isotope geochemistry of copper

carbonates at the Northwest Extension deposit, Morenci District, Arizona:

implications for conditions of supergene oxidation and related

mineralization. Economic Geology, 98, 607-621.

Misra, D.N. (1999) Interaction of citric or with calcium

fluorapatite: precipitation of calcium fluoride. Journal of Colloid and

Interface Science, 220, 387-391.

Nickel, E.H., Clout, J.F.M. and Gartrell, B.J. (1994) Secondary nickel minerals from

Widgiemooltha, Western Australia. The Mineralogical Record, 25, 283-291,

302.

136 Norman, N.C. (1998) Chemistry of Arsenic, Antimony and Bismuth. Blackie,

London.

Ondruš, P., Veselovský, F., Sejkora, J.S., Pažout, R., Frýda, J., Gabašová, A. and

Vajdak, J. (2006) Lemanskiite, NaCaCu5(AsO4)4Cl·5H2O, a new mineral

species from the Abundancia mine, Chile. The Canadian Mineralogist, 44,

523-531.

Osborne, I. (1975) Annual Report Compilation, Glen Innes, Glen Elgin, Kingsgate –

Dorrigo/Grafton Sheet, 1875-1975. New South Wales Department of

Primary Industries (Mineral Resources) Open File Report, No. R00051314,

entry 13/64.

O'Sullivan, P.B., Gibson, D.L., Kohn, B.P., Pillans, B. and Pain, C.F. (2000) Long-

term landscape evolution of the Northparkes region of the Lachlan Fold

Belt, Australia: constraints from fission track and paleomagnetic data.

Journal of Geology, 108, 1-16.

Otto, H.H. and Strunz, H. (1968) Zur kristallchemie synthetischer blei-wismut-

speissglanze. Neues Jahrbuch für Mineralogie, Abhandlung, 108, 1-19.

Perrin, D.D. and Sayce, I.G. (1967) Computer calculation of equilibrium

concentrations in mixtures of metal ions and complexing species. Talanta,

14, 833-842.

Pillans, B. (2004) Geochronology of the Australian regolith. In: Anand, R.R. and de

Broekert, P. (Eds) Regolith Evolution Across Australia., CRC LEME, Perth.

137 Pillans, B., Tonui, E. and Idnurm, M. (1999) Paleomagnetic dating of weathered

regolith. In: Taylor, G. and Pain, C. (Eds) New Approaches to an Old

Continent, Proceedings of the Regolith 98 Conference, Kalgoorlie, CRC

LEME, Perth, 237-242.

Plimer, I.R. (1975) Wolfram Camp wolframite-molybdenite-bismuth-quartz pipes,

north Queensland. In: Knight, C.L. (Ed.) Economic Geology of Australia

and Papua New Guinea - 1. Metals. Australasian Institute of Mining and

Metallurgy, Melbourne, Monograph Series, 5, 760-762.

Plimer, I.R. (1977) Bismuth minerals from quartz pipes in eastern Australia.

Australian Mineralogist. 10, 41-43.

Pollard, A.M., Thomas, R.G. and Williams, P.A. (1989) Synthesis and stabilities of

the basic copper(II) chlorides atacamite, paratacamite and botallackite.

Mineralogical Magazine, 53, 557-563.

Posnjak, E. and Merwin, H.E. (1922) The system, Fe2O3–SO3–H2O. Journal of the

American Chemical Society, 44, 1965–1994.

Post, J.E. (1999) Manganese oxide minerals: crystal structures and economic and

environmental significance. Proceedings of the National Academy of

Sciences of the United States of America, 96, 3447-3454.

Pring, A., Jercher, M. and Makovicky, E. (1999) Disorder and compositional

variation in the lillianite homologous series. Mineralogical Magazine, 63,

917-926.

138 Prodan, A., Bakker, M., Versteegh, M. and Hyde, B.G. (1982) A microscopic study

of synthetic PbS-rich homologues nPbS-mBi2S3. Physics and Chemistry of

Minerals, 8, 188-192.

Rankin, J., Sharpe, J.L. and Williams, P.A. (2001) Betpakdalite from the tin deposits

of Elsmore, New England district of New South Wales. Australian Journal

of Mineralogy, 7, 15-17.

Rankin, J., Lawrence, L.J., Sharpe, J.L. and Williams, P.A. (2002) Rare secondary

bismuth, tungsten and molybdenum minerals from Elsmore, New England

district of New South Wales. Australian Journal of Mineralogy, 8, 55-60.

Robertson, I.D.M., King, J.D. and Anand, R.R. (2001) Regional geology and

geochemical exploration around the Stellar and Quasar gold deposits, Mt

Magnet, Western Australia. Geochemistry: Exploration, Environment,

Analysis, 1, 353-364.

Robie, R.A. and Hemingway, B.S. (1995) Thermodynamic properties of minerals

and related substances at 298.15K and 1 bar (105 Pascals) pressure and at

higher temperatures. United States Geological Survey Bulletin, 2131.

Ryall, W.R. and Segnit, E.R. (1976) Minerals of the oxidised zone of the Dome Rock

copper deposit, South Australia. Australian Mineralogist, 2, 5-8.

Sarafian, P.G. and Furbish, W.J. (1965) Solubilities of natural and synthetic

ferrimolybdite. American Mineralogist, 50, 223-226.

Segnit, E.R. (1976) Scorodite from Dome Rock, South Australia. Australian

Mineralogist, 2, 35.

139 Segnit, E.R. (1978) Further minerals from the Dome Rock Mine, South Australia.

Australian Mineralogist, 15, 73-74.

Shannon, R.D. (1976) Revised effective ionic radii and systematic studies of

interatomic distances in halides and chalcogenides. Acta Crystallographica

A, 32, 751-767.

Sharpe, J. L. and Williams, P.A. (2004) Secondary bismuth and molybdenum

minerals from Kingsgate, New England district of New South Wales.

Australian Journal of Mineralogy, 10, 7-12.

Sheldrick, G.M. (1996) SADABS: Empirical Absorption Correction Program for

Area Detector Data. University of Göttingen, Göttingen, Germany.

Sheldrick, G.M. (1997a) SHELXS97: A Program for the Solution of Crystal

Structures. University of Göttingen, Göttingen, Germany.

Sheldrick, G.M. (1997b) SHELXL97, A Program for the Refinement of Crystal

Structures. University of Göttingen, Göttingen, Germany.

Shields, P.W. (1996) Geology of the Girilambone copper deposit. In: Cook, W.G.,

Ford, A.J.H., McDermott, J.J., Standish, P.N., Stegman, C.L. and Stegman,

T.M. (Eds) The Cobar Mineral Field - a 1996 Perspective, Australasian

Institute of Mining and Metallurgy, Melbourne, 293-304.

Simpson, C.J. (1967) Kingsgate molybdenum-bismuth prospect – final report. New

South Wales Department of Primary Industries (Mineral Resources) Open

File Reports, No. R00027780.

140 Skirrow, R.G. (2002) Copper-gold-bismuth deposits of the Tennant Creek district,

Australia: a reappraisal of diverse high-grade systems. In: Porter, T.M. (Ed.)

Hydrothermal Iron-Oxide Copper-Gold and Related Deposits. PGC

Publishing, Adelaide, 149-160.

Smith, G. (1913) Mine Record 1567, 25/5/1913. New South Wales Department of

Primary Industries (Mineral Resources) Open File Report, No. R00046461

and R00046462.

Smith, G. (1926) A Contribution to the Mineralogy of New South Wales. New South

Wales Department of Mines, Geological Survey, Mineral Resources Series,

No. 34.

Smith, R.M. and Martell, A.E. (1976) Critical Stability Constants. Volume 4:

Inorganic Complexes. Plenum Press, New York.

Smith, R.M. and Martell, A.E. (1989) Critical Stability Constants. Volume 6: Second

Supplement. Plenum Press, New York.

Sparks, D.L. (2001) Elucidating the fundamental chemistry of soils: past and recent

achievements and future frontiers. Geoderma, 100, 303-319.

Stegman, C. and Reynolds, I. (2005) Primary mineralisation in Cobar deposits, with

emphasis on gold deposits of the Cobar Goldfield. Australian Journal of

Mineralogy, 11, 63-72, and references therein.

Strunz, H. and Nickel, E.H. (2001) Strunz Mineralogical Tables. 9th Edition. E.

Schweizerbart’sche Verlagsbuchhandlung, Stuttgart.

141 Sullivan, H.B. (1883) Plan of Portion ML 34. New South Wales Department of

Primary Industries (Mineral Resources) Open File Report, No. R13014400.

Taylor, P., Sunder, S. and Lopata, V.J. (1984) Structure, spectra, and stability of

solid bismuth carbonates. Canadian Journal of Chemistry, 62, 2863-2873.

Thurston, J.H., Swenson, D.C. and Messerle, L. (2005) Solvolytic routes to new

nonabismuth hydroxy- and alkoxy-oxo complexes: synthesis,

characterization and solid-state structures of novel nonabismuth polyoxo

5+ cations Bi9( 3-O)8 ( 3-OR)6 (R: H, Et). Chemical Communications, 4228-

4230.

Tonui, E., Jones, R. and Scott, K. (2002) Regolith mineralogy and geochemical

dispersion at the Northparkes Cu-Au deposits, New South Wales, Australia.

Geochemistry, Exploration, Environment, Analysis, 2, 346-360. van der Ende, J. (1991) Supersaturation of soil solutions with respect to gypsum.

Plant and Soil, 133, 65-74. van der Lee, J. and Lomenech, C. (2004) Towards a common thermodynamic

database for speciation models. Radiochimica Acta, 92, 811-818.

Vogl, J.F. (1853) Lindackerit, eine neue Mineralspecies, und lavendulan von

Joachimsthal, nebst Bemerkungen über die Erzfürung die Gänge. Jahrbuch

der Kaiserlich-königlichen Geologischen Reichsanstalt, 4, 552-557.

Wallner, H., Preis, W. and Gamsjäger, H. (2002) Solid-solute phase equilibria in

aqueous solutions XV. Thermodynamic analysis of the solubility of nickel

carbonates. Thermochimica Acta, 382, 289-296.

142 Watt, J.A. (1898) Notes on the Occurrence of Bismuth Ores in New South Wales.

New South Wales Department of Mines, Geological Survey, Mineral

Resources Series, No. 4.

Weber, C.R., Paterson, I.B.L. and Townsend, D.J. (1978) Molybdenum in New South

Wales. Geological Survey of New South Wales Mineral Resources Series,

43.

Wilkinson, C.S. (1884) Annual Report of the Department of Mines and Agriculture

for 1883. Department of Mines and Agriculture, New South Wales, 154-

155.

Williams, P.A. (1990) Oxide Zone Geochemistry. Ellis Horwood, Chichester.

Zakrzewski, M.A. and Makovicky, E. (1986) Izoklakeite from Vena, Sweden, and

the kobellite homologous series. The Canadian Mineralogist, 24, 7-18.

Zhu, Y. and Merkel, B.J. (2001) The dissolution and solubility of scorodite,

FeAsO4·2H2O: Evaluation and simulation with PHREEQC2.

Wissenschaftliche Mitteilungen: Institut für Geologie der Technische

Universität Bergakademie Freiberg, 18, 72-87.

Zirino, A. and Yamamoto, S. (1972) A pH-dependent model for the chemical

speciation of copper, , cadmium and lead in seawater. Limnology and

Oceanography, 17, 661-671.

Zubkova, N.V., Pushcharovsky, D.Y., Sarp, H., Teat, S.J. and MacLean, E.J. (2003)

Crystal structure of zdenekite NaPbCu5(AsO4)4Cl·5H2O. Crystallography

Reports, 48, 939-943.

143