BISMUTH IN THE SUPERGENE ENVIRONMENT
Timothy D. Murphy BSc (Hons), UWS
This thesis is submitted for the degree of
Doctor of Philosophy
in the University of Western Sydney
Supervisors: Professor Peter A. Williams and Professor Peter Leverett
March 2015
ACKNOWLEDGEMENTS
I sincerely thank my supervisor Professor Peter Williams, for sharing his extensive knowledge in chemistry and mineralogy which made the project possible. His guidance, support and encouragement throughout has been greatly appreciated. I would also like to thank my co-supervisor Professor Peter Leverett for his invaluable assistance and perspectives on my thesis which have been greatly appreciated. Dr Ric
Wuhrer and the Advanced Materials Characterisation Facility provided assistance with
X-ray diffraction as well as support, guidance and equipment training. Jim Sharp is thanked for his assistance with fieldwork and sharing his experience in mineralogy and
X-ray diffraction. John Rankin is acknowledged for sharing his knowledge on the mineralogy of the New England Oregon.
I would like to thank my fellow PhD students Matthew Sciberras, Adam Roper,
Mitchel Nancarrow and Simon Hager for their invaluable help, support and friendship throughout the project. Finally I would like to thank the people who have helped and encouraged me outside of the academic environment throughout this endeavour, especially my Mother, Father and Sister whose help, support, encouragement and love have helped me become the person I am today, as well as my friends.
STATEMENT OF AUTHENTICATION
This thesis contains work that, to the best of my knowledge and belief, is original except where due acknowledgment appears in the text. I declare that material in this thesis has not been submitted in any form for a degree or diploma at any other university or institution of tertiary education.
...... …………………
Timothy David Murphy
March 2015
TABLE OF CONTENTS
Chapter 1 Introduction 1
1.1 Abstract 2 1.2 Geochemical Exploration 3 1.3 Bismuth as a path finder element 6 1.4 Project Outline 13 1.5 References 13
Chapter 2 Bismoclite, Bismtutite, Cannonite and Riomarinaite 22
2.1 Abstract 23 2.2 Introduction 23 2.2.1 Bismite, bismoclite, bismutite, cannonite and riomarinaite 23
2.2.2 Rare and other bismuth oxide, carbonates, chloride, and sulfate minerals 26
2.3 Experimental 28 2.3.1 Syntheses of cannonite and riomarinaite 28 2.3.2 Solubility Studies 29 2.4 Results 30 2.4.1 Synthesis of cannonite and riomarinaite 30 2.4.2 Solubility Studies 30 2.5 References 40
Chapter 3 Rooseveltite, Preisingerite and Atelestite 45
3.1 Abstract 46 3.2 Introduction 46 3.3 Experimental 50 3.3.1 Syntheses of rooseveltite, tetrarooseveltite, atelestite and preisingerite 50 3.3.2 Solubility Studies 51 3.4 Results 51 3.4.1 Syntheses of rooseveltite, tetrarooseveltite, atelestite and preisingerite 51 3.4.2 Solubility Studies 55 3.5 References 60
Chapter 4 Russellite, Koechlinite and Sardignaite 66
4.1 Abstract 67 4.2 Introduction 67 4.3 Experimental 73 4.3.1 Syntheses of russellite, koechlinite and sardignaite 73 4.3.2 Solubility Studies 74 4.4 Results 75 4.4.1 Syntheses of russellite, koechlinite and sardignaite 75 4.4.2 Solubility Studies 79 4.5 References 84
Chapter 5 Smirnite and Chekhovichite 90
5.1 Abstract 91 5.2.1 Introduction 91 5.3 Experimental 94 5.3.1 Syntheses of smirnite and chekhovichite 94 5.3.2 Solubility Studies 95 5.4 Results 95 5.4.1 Syntheses of smirnite and chekhovichite 95 5.4.2 Solubility Studies 98 5.5 References 102
Chapter 6 Conclusion 105
6.1 Abstract 106 6.2 Introduction 106 6.3 Discussion of Data 108 6.3.1 Chapter 2 Discussion 108 6.3.2 Chapter 3 Discussion 110 6.3.3 Chapter 4 Discussion 112 6.3.4 Chapter 5 Discussion 114 6.4 Reverse Ground Water Modelling 116
6.5 Bismuth Model for the Cobar Region 117 6.6 Bismuth Model for the New England Region 125 6.7 Conclusion 130 6.8 References 131
Appendix A 137
CHAPTER 1
INTRODUCTION
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1.1 ABSTRACT
Bismuth minerals associated with Mo, W, and Sn, are often found amongst the highly acidic deposits of the eastern ranges of Australia (Plimer, 1975; Weber et al.,
1978). It is important to gain an understanding of the mobility and dispersion of Bi in the supergene zone and make an assessment of these areas, as they have been the focus for geochemical exploration to develop prospects and mining operations. A review of the literature on bismuth as a pathfinder element, with respect to its ground water and regolith concentrations, uncovered significant documentation including scientific, industrial and government reports, the use of various sampling methods, and the use of assumptions in previous studies due to the information and techniques available at the time (MacDuff, 1971; 1971a; 1971b; 1972; Siegal, 1974; Roes et al., 1979; Levinson,
1980; Plant et al., 1989; Plant et al., 1991; Fiella; 2010). Furthermore, information on the Gibbs free energy of formation values was limited to 3 out of the 65 known bismuth secondary minerals (Clissold, 2007).
A study on a range of secondary bismuth minerals in the supergene zone,
(Rankin et al., 2001, 2002; Sharpe and Williams, 2004) showed that even though bismuth minerals are considered to be rare, localised areas of Bi concentration are in fact quite common. Examples of this can be found in certain deposits in eastern
Australia such as the New England Orogen. Therefore, the geochemical modelling carried out in this thesis has focused on eastern Australia and examines potential impacts on geochemical exploration where Bi has been used as a pathfinder element.
Furthermore this work can be been applied to exploration sites around the world where
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Bi is employed as a pathfinder element. To do this, a rigorous investigation including
Bi mineral synthesis, solubility and stabilities was undertaken thus yielding an assessment of the suitability of bismuth as a pathfinder for future geochemical surveys.
1.2 GEOCHEMICAL EXPLORATION
Due to the nature and growth of manufacturing and consumption worldwide and the need for mineral resources to meet these demands, the discovery of large-scale near-surface deposits are in decline and thus the push to find deeper deposits has inevitably increased (Aspandiar et al., 2008). Therefore, it is necessary to constantly review and scrutinise new, current and historic exploration techniques to discover hidden ore bodies that are commercially significant. Exploration geochemistry is used in virtually every exploration program whereby geochemical prospecting for minerals include any method of mineral exploration based on systematic measurement of one or more chemical properties of a natural occurring material e.g. Hawkes and Webb, 1962.
The earliest reports of geochemical research date back to the 1930’s which were carried-out in the former Soviet Union, and were known as metallometric surveying, which we know today as geochemical surveys (Hawkes and Webb, 1962). It was not until the late 1930’s to 1940’s that there was a rise in geochemical research by Western countries, largely due to the increased resource requirements of World War II. Since then, geochemical exploration methods have become increasingly sophisticated due to advances in analytical instrumentation, yet much is still to be discovered and a greater understanding to be obtained
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Geochemical exploration strategies include a number of key phases such as planning, sampling, chemical analysis, interpretation and follow-up. Each stage is critical and exploration geologists have to be cautious at each phase to ensure the integrity of the data that is to be applied to the succeeding stages. Although for a variety of commodities, or for a specifically targeted commodity, most deposits in a given geological setting have, on average, the same profile or type deposit settings with respect to elemental dispersion characteristics over regional landscapes. However, specific environments within this may contain deposits with a degree of uniqueness (i.e. geochemical signature) due to the differences in the geological, geomorphological and environmental setting. Furthermore, many localities have well documented information from which geochemical exploration studies can be undertaken while others do not.
One of the greatest challenges in geochemical surveys is the confidence to distinguish between anomalous and background concentration in soils and ground waters. A review of mining reports and reported data created by Siegal (1974), Rose et al. (1979), Roes et al. (1979), Levinson (1980), Plant et al. (1989) and Plant et al. (1991) provide a solid in site. However, due to the targeted nature of these reports extraction of additional data requires the application of newer analytical methods which were/may not have been available (or un-needed for the specific task) at the time. For example, for the elements
Bi and W, in some cases (MacDuff, 1971; 1971a; 1971b; 1972 and Fiella, 2010) reports have honestly stated that because of a lack of references in the literature to similar sampling programs, the results of their survey and previous data have to be arbitrarily interpreted.
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Exploration across depositional landforms, both simple and complex, and with shallow to deep transported regolith cover by using various geochemical techniques has reaffirmed the important need to conduct and understand surface geochemistry and to make it effective for new green field locations. Australia exhibits a unique landscape with many of the landforms having their origins 300 Ma ago at the beginning of the break-up of Gondwana (Aspandiar, 2008). Since that time the Australian land mass has been exposed to wide ranging climatic conditions, from tropical to glacial periods as well as undergoing various tectonic events which have been well documented (Anand,
2005). The impact of these weathering events has impacted the chemical and physical environment which has resulted in continuous alteration of exposed rocks (Anand,
R.R., 2005). Furthermore, during most of the Phanerozoic era (0 to 540 Ma), eastern and south-eastern Australia were undergoing active plate tectonic processes leading to the amalgamation of various accreted terranes from east to west from approximately
550 Ma up to approximately 200 MA. It has only been recently, during the Quaternary period where the weathered crust has mostly formed over the last few million years.
This has preserved the weathered mantle as a wide spread cover, 20 to 100m thick, over much of the landscape. Therefore, weathering in a geochemical exploration context causes the destruction of primary ore deposits and the dispersion of ore and pathfinder elements into the surrounding regolith. Conversely, it may also result in the supergene enrichment of some deposits and promote the formation of secondary ore bodies. To understand the history and potential mechanisms and pathways of migration of ore and pathfinder elements in regolith, it is necessary to resolve the complex superposition of events that may have occurred during regolith-landscape evolution.
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1.3 BISMUTH AS A PATHFINDER ELEMENT
Bismuth is a rare element which is 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; Lang and Baker, 2001; Baker et al.,
2005). 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
Figure 1.1: Location of the Cobar, Kingsgate, Wolfram Camp, Tennant Creek and
Henty and Mt Julia mines.
context (Figure 1.1) accessory Bi mineralisation is a feature of the Cobar- style deposits
(Stegman and Reynolds, 2005), the Henty and Mount Julia gold deposits, Tasmania
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(Callaghan, 2001), certain deposits in the Western Australian shield (Roberson et al.,
2001; Hassan and Clarke, 2005) and the Cu-Au-Bi deposits of the Tennant Creek area,
Northern Territory (Skirrow, 2002). Bismuth minerals are also important constituents of the New England Orogen of eastern Australia (Figure 1.2), where they have reported associations with Mo, W and Sn, and with highly acidic and very rich (albeit of low tonnage) gold deposits of the eastern ranges of Australia (Plimer, 1975; Weber et al.,
1978). It is important to remember that this group of sites is indicative only, and is far from being comprehensive but allows for a good starting point for the study of accessory mineralisation of their target materials.
Figure 1.2: Location map showing the distribution of eastern Australian
orogens (Champion, 2009).
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Bi has been extensively used as a pathfinder element in geochemical exploration for a variety of deposits (Angino and Long, 1979; Hale, 1981; Robertson et al., 2001;
Collins et al., 2004). The behaviour of Bi in terms of its solution speciation as a function of pH is well-established (Baes and Mesmer, 1976; Smith and Martell, 1976:
Norman, 1998; Thurston et al., 2005) and provides a general first order assessment of its mobility in pore solution in the regolith. However, very little is known of the chemistry of formation of secondary Bi species in the supergene zone or of their stabilities. To build on existing knowledge a more comprehensive understanding of the dispersion of Bi in the regolith requires detailed study of its low-temperature aqueous chemistry, and the investigation of the secondary Bi minerals that serve to buffer the element between the solid and solution states.
Bismuth is estimated to have an average crustal abundance of 8.5 ppb and is highly fractionated (Emsley, 1991). Mafic to intermediate igneous rocks average 40 ppb, whereas rhyolites and granites average 900 and 270 ppb, respectively. However, not all granites exhibit this degree of enrichment (Lueth, 1999). Sedimentary rocks contain higher amounts, with shales having the greatest average (0.26 ppm) and limestone 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) reported an average Bi concentration in soils of 0.2 ppm, much lower than previous reports in the literature where the limits of detection were 5 ppm (McDuff and Snow, 1971).
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To understand the use of bismuth as a pathfinder element in fresh and marine waters, Filella (2010) collated and critiqued data and analytical techniques from 125 published papers and tested methods to establish a reasonable typical range of total dissolved bismuth in natural waters. She concluded that this was impossible to achieve due to the wide, unexplained and dated dispersion of the data, as well as inadequate limits of detection of past and present analytical techniques based on literature published to date. Furthermore, Filella (2010) asserted that it was not possible to make a confident estimation of bismuth concentrations in seawater and that it was also not possible to identify a range of probable concentration values for fresh waters which were not heavily polluted. Thus, in most cases, the use of bismuth as a pathfinder element is untested to draw any conclusions for the geochemist with respect to background concentrations or anomalous values.
Like bismuth, tellurium is also used as a geological pathfinding element due to its occurrence and association with ore-forming elements in hydrothermal deposits
(McPhail, 1995). The speciation of Te has been established (McPhail, 1995) and the thermodynamic properties for Te-bearing mineral, aqueous and gaseous species have been reported (Ahmad et al., 1987; Afifi et al., 1988; Jaireth, 1991; Zhang and Spry,
1994; McPhail, 1995). The literature to date forms a solid starting point to assess the role Te plays in different mineral systems, yet the exact thermodynamic and solubility data for specific minerals in various geochemical settings are still to be reported. With this in mind, along with themes presented in previous chapters, there are a number of reports from geological surveys of various environments (Lett et al. 1998) where Te and Bi anomaly values have been reported. However, these numbers are arbitrarily derived or are at the limit of the analytical technique used.
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To understand the dispersion of bismuth in the supergene environment a review of the secondary bismuth minerals and their occurrences has been undertaken which is summarised in Table 1.1. In-depth reviews of specific minerals are indicated at the beginning of chapters 2 to 5.
Table 1.1 The secondary minerals of bismuth. The number after the formula is the
number of known occurrences as listed by Mindat.org.
Aiolosite Na2(Na2Bi)(SO4)3Cl 1 “Arsenowaylandite” BiAl3(AsO4)2(OH)6 1 1,2 Asselbornite Pb(BiO)3(UO2)4(AsO4)2(OH)7·4H2O 2 Atelestite Bi2(AsO4)O(OH) 35 Beyerite Ca(BiO)2(CO3)2 27 Bismite Bi2O3 174 Bismoclite BiOCl 50 Bismutite (BiO)2CO3 543 Bismutoferrite Fe2Bi(SiO4)2(OH) 47 “Bismutostibiconite” BiSb2O7 6 1 3+ Bleasdaleite (Ca,Fe )2Cu5(Bi,Cu)(PO4)4(H2O,OH,Cl)13 1 3+ Bouazzerite Bi6(Mg,Co)11Fe 14(AsO4)18(OH)4·86H2O 1 3+ 2+ Brendelite (Bi,Pb)2(Fe ,Fe )(PO4)O2(OH) 2 Cannonite Bi2(SO4)O(OH)2 16 Chekhovichite Bi2Te4O11 4 1 Chiluite Bi3TeMoO10.5 1 Chrombismite Bi16CrO27 1 Clinobisvanite BiVO4 32 3+ 3+ Cobaltneustädtelite Bi2Fe (Co,Fe )2(AsO4)2(OH,O)4 6 Daubréeite BiO(OH,Cl) 10 Dreyerite BiVO4 3 Dukeite Bi24Cr8O57(OH)6·3H2O 2 Francisite Cu3Bi(SeO3)2O2Cl 2 6+ 5+ Gelosaite BiMo (2-5x)Mo 6xO7(OH)·H2O 2 Hechtsbergite Bi2(VO4)O(OH) 4 1 Juanitaite Bi(Cu,Ca,Fe)10(AsO4)4(OH)11·2H2O 4 Kettnerite CaBi(CO3)OF 29 Koechlinite Bi2MoO6 26 3+ 3+ Medenbachite Bi2Fe (Cu,Fe )(AsO4)2(OH,O)4 3 Mixite BiCu6(AsO4)3(OH)6·3H2O 139 1 Montanite Bi2TeO6·2H2O; Bi2(OH)4TeO4 19 Mrázekite Bi2Cu3(PO4)2O2(OH)2·H2O 10 Namibite Cu(BiO)2(VO4)(OH) 23 3+ 3+ Neustädtelite Bi2Fe (Fe ,Co)2(AsO4)2(OH,O)4 16 Nickelschneebergite (Bi,Ca)(Ni,Co,Fe)2(AsO4)2·2(OH,H2O) 1 Orthowalpurgite (BiO)4(UO2)(AsO4)2·2H2O 1 Paganoite NiBi(AsO4)O 1
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Paulkellerite (BiO)2Fe(PO4)(OH)2 1 Perite PbBiO2Cl 16 Petitjeanite Bi3(PO4)2O(OH) 13 3 Phosphowalpurgite (BiO)4(UO2)(PO4)2 3 Pingguite Bi6Te2O13 3 1 Pottsite HPbBi(VO4)2·2H2O 3 Preisingerite Bi3(AsO4)2O(OH) 39 Pucherite BiVO4 46 Riomarinaite BiSO4(OH)·H2O 2 Rooseveltite BiAsO4 26 Russellite Bi2WO6 23 Sardignaite BiMo2O7(OH)·2H2O 1 Schlegelite Bi7(AsO4)3(MoO4)2O4 1 Schneebergite (Bi,Ca)(Co,Ni,Fe)2(AsO4)2·2(OH,H2O) 2 Schumacherite Bi3(VO4)2O(OH) 11 Sillénite Bi12SiO20 14 Smirnite Bi2TeO5 4 4 Smrkovecite Bi2(PO4)O(OH) 2 Sphaerobismoite Bi2O3 2 5 Šreinite Pb(BiO)3(UO2)4(PO4)2(OH)7·4H2O 1 Tetrarooseveltite BiAsO4 1 Uranosphaerite Bi(UO2)O2(OH) 17 Walpurgite (BiO)4(UO2)(AsO4)2·2H2O 31 Waylandite BiAl3(PO4)2(OH)6 25 Ximengite BiPO4 3 1 Yecoraite Fe3Bi5(TeO4)2O9·9H2O 5 Zaïrite Bi(Fe,Al)3(PO4)2(OH)6 2 Zavaritskite BiOF 12 1Structure unknown. 2Arsenate analogue of šreinite. 3Walpurgite structure type. 4Atelestite structure type. 5Structure unknown; phosphate analogue of asselbornite; “ “ unapproved mineral species. Chemical formulae and mineral approval status derived from the IMA mineral database list (Rakovan, 2007).
An inspection of Table 1.1 indicates that the most common phases reported are bismutite, bismite, mixite and bismoclite. Stoichiometries indicated in Table 1.1 are based for the most part on single-crystal X-ray determinations (Anthony et al., 1990;
1995; 1997; 2000; 2003) and reference is made to these where appropriate or to other sources for more recent structure determinations. Topographical listings in mindat.org are recognised as being imperfect and other localities for a number of the secondary minerals may be gleaned from the literature (vide infra). Nevertheless, the tabulation
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To gain a better understanding and to develop a comprehensive base-line of the distribution of secondary Bi mineralogy with respect to prospecting in Australia, a preliminary study on the frequency, occurrence and associates is summarised in
Appendix A Some of the results are based upon more than 150 powder X-ray diffraction determinations (Rankin et al., 2002; Sharpe and Williams, 2004). A further study of some 40 specimens from the collections of the Australian Museum has provided supplementary data for other deposits; rare minerals were encountered but a distribution pattern of common phases does emerge.
This in turn has a bearing on the selection of species that should be incorporated in any supergene dispersion model for Bi as several minerals, cannonite,
Bi2(SO4)O(OH)2, for example, are seen to be important even though they are found to be rare. Of course, each secondary mineral has its own geochemical history and can only be formed as a result of appropriate prevailing redox, temperature and concentration conditions; some may be metastable with respect to others. However, with a view towards a functional model for their influence on bismuth dispersion in the regolith, very rare species may be largely passed over because they almost certainly form under geochemical conditions that are rarely encountered.
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1.4 PROJECT OUTLINE
In summary, the deficiency in the interpretation of Bi anomalies in the regolith formed as a result of the oxidation of primary Bi-bearing mineralisation and forms the basis of the argument for this thesis. To draw conclusions on a proper understanding of the dispersion of Bi in the environment will depend on appreciation of its low- temperature aqueous chemistry and knowledge of the secondary Bi minerals that serve to buffer the element between the solid and solution states. Of the known bismuth minerals reliable thermodynamic data are available only for bismite, bismoclite and bismutite. This highlights the gap in the literature when attempting to construct a model for the stability and dispersion of the bismuth secondaries. To determine their solubility, calculations have been made to deduce reasonable values of bismuth in ground waters (discussed in Chapter 6). The common and key phases that were taken into account in this work included:
The minerals bismite, bismoclite, bismutite, cannonite, and riomarinaite,
discussed in Chapter 2.
The minerals rooseveltite, tetrarooseveltite, preisingerite and atelestite discussed
in Chapter 3.
The minerals koechlinite, russellite, and sardignaite discussed in Chapter 4.
The minerals cherckovivhite and smirnite, discussed in Chapter 5.
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1.5 REFERENCES:
Afifi, A., Kelly, M., and Essene, E.J. (1988) Phase relationships among tellurides,
sulphides and oxides: I. Thermochemical data and calculated equilibria. Economic
Geology, 83, 337-394.
Anand, R.R. (2005) Weathering history, landscape evolution and implications for
exploration In: Anand, R.R. and de Broekert, P. (Eds.) "Regolith Landscape
Evolution Across Australia: a compilation of regolith landscape case studies with
regolith landscape evolution models" CRC LEME 1v, p2-40.
Ahmad, M. Solomon, M., and Walshe, J.L. (1987) Mineralogical and geochemical
studies of the Emperor gold telluride deposit, Fiji. Economic Geology, 82, 234-270.
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.
Angino, 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.
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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, Sulfates. Mineral Data Publishing,
Tucson, Arizona.
Aspandiar, M.F., Anand, R.R. and Gray, D.J., (2008) Geochemical dispersion
mechanisms through transported cover: Implications for mineral exploration in
Australia. CRC-LEME, CSIRO Open File Report Series, 230R.
Baes, C.F. Jr and Mesmer, R.E. (1976) The Hydrolysis of Cations. Plenum Press, New
York.
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.
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Brooks, R. R. (1972) Geobotany and biogeochemistry in mineral exploration: New
York, Harper and Row, 290 p
Brandenstein, M., Janda., I. and Schroll, E. (1960) Seltene elemente in österreichischen
kohlen- und bitumengesteinen. Tschermaks Mineralogische und Petrographische
Mitteilungen, 7, 260-269.
Callaghan, T. (2001) Geology and host-rock alteration of the Henty and Mount Julia
gold deposits, western Tasmania. Economic Geology, 96, 1073-1088.
Champion, D.C., Kositcin, N., Huston, D.L., Mathews, E. and Brown, C. (2009)
Geodynamic Synthesis of the Phanerozoic of eastern Australia and implications for
metallogeny. Geoscience Australia Record 2009/18, 255 p.
Clissold, M.E. (2007) Aspects of the supergene geochemistry of copper nickel and
bismuth. PhD thesis unpbulished, University of Western Sydney.
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 Roberson, I.D.M.
(Eds), Regolith Expression of Australian Ore Systems. CRC LEME, Perth, pp. 1-3.
Emsley, J. (1991) The Elements. Second edition, Oxford University Press, Oxford.
Filella, M. (2010) How reliable are environmental data on 'orphan' elements? The case
of bismuth concentrations in surface waters. Journal of Environmental Monitoring,
12, 90-109.
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Goldschmidt, V.M. (1970) Geochemistry. Oxford University Press, Oxford.
Hale, M., (1981) Pathfinder applications of arsenic, 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.
Hawkes, H.E. and Webb, J.S. (1962) Geochemistry in Mineral Exploration. Harper and
Row, New York.
Jaireth, S. (1991) Hydrothermal geochemistry of Te, Ag2Te, and AuTe2 in epithermal
precious metal deposits. Economic Geology, 37. James Cook University of North
Queensland, Australia.
Kabata-Pendias, A. (2001) Trace Elements in Soils and Plants. 3rd Edition, CRC Press,
Boca Raton, Florida.
Lang, J.R. and Baker, T. (2001) Intrusion-related gold systems: the present level of
understanding. Mineralium Deposita, 36, 477-489.
Lett, R.E., Jackaman, W. and Yeow, A. (1998) Detailed Geochemical Exploration
techniques for base and precious metals in the Kootenay Terrane. Geological
Fieldwork 1998. 297-306.
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Levinson, A.A., (1980) Introduction to Exploration Geochemistry: The Supplement,
Applied Publishing Ltd, Wilmette, USA, 1980, 615-924.
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
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Norman, N.C., (1998) Chemistry of Arsenic, Antimony and Bismuth. Blackie, London.
Plant, J.A., Breward, N., Forrest, M.D. and Smith, R.T. (1989) The gold pathfinder
elements As, Sb and Bi - their distribution and significance in the southwest
Highlands of Scotland. Transactions of the Institution of Mining and Metallurgy,
98, B91-101.
Plant, J.A., Cooper, D.C., Green, P.M., Reedman, A.J. and Simpson, P.R. (1991)
Regional distribution of As, Sb and Bi in the Grampian Highlands of Scotland and
English Lake District: implications for gold metallogeny. Transactions of the
Institution of Mining and Metallurgy, 100, B135-147.
Plimer, I., (1975) Wolfram Camp wolframite-molybdenite-bismuth-quartz pipes, north
Queensland. In: N 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.
Rakovan, J. (2007) Words to the Wise- More than 4000 To Be Exact. Rocks and
Minerals, 82, 423-424.
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.
19 | P a g e
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.
Roberson, 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.
Rose, A.W., Hawkes, H.E. and Webb, J.S., (1979) Geochemistry in Mineral
Exploration Academic Press, New York, N.Y., pp. 490--517.
Siegel, F. R., (1974) Applied Geochemistry: New York, John Wiley and Sons, 353p.
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.
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, pp. 149-160.
Smith, R.M. and Martell, A.E., (1976) Critical Stability Constants. 4. Inorganic
Complexes. Plenum Press, New York.
20 | P a g e
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.
Thurston, J.H., Swenson, D.C. and Messerle, L., (2005) Solvolytic routes to new
nonabismuth hydroxy- and alkoxy-oxo complexes: synthesis, characterization and
5+ solid-state structures of novel nonabismuth polyoxo cations Bi9(μ3-O)8 (μ 3-OR)6
(R: H, Et). Chemical Communications, 4228-4230.
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.
Zhang, X. and Spry, P.G. (1994) Calculated stability of aqueous tellurium species,
calaverite, and hessite at elevated temperatures, Economic Geology, 87, 1152-
1166.
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CHAPTER 2
BISMOCLITE, BISMUTITE, CANNONITE AND RIOMARINAITE
22 | P a g e
2.1 ABSTRACT
From studying the relative frequency, associations and occurrence of secondary
Bi minerals found from a host of deposits, bismite, Bi2O3, bismoclite, BiOCl, bismutite, (BiO)2CO3, and cannonite Bi2(SO4)O(OH)2 appear to play a significant role in the immobilisation of Bi in oxidised settings. Thus, these phases are important in developing a preliminary model for the dispersion of Bi in the supergene environment.
ө Thermochemical data was determined for cannonite, ΔGf (Bi2(SO4)O(OH)2, 298.15K)
= –1315.98±0.5 kJ mol–1, allowing for the development of a geochemical model.
Understanding the immobilising capacity of these important secondary minerals, under various conditions, further develops our understanding of the dispersion and mobility of bismuth in the supergene zone.
2.2 INTRODUCTION
The minerals of interest that were studied in this chapter were bismite, bismoclite, bismutite, cannonite and riomarinaite. The discovery and associations are discussed below in section 2.2.1. These were chosen due to their known associations and their common assemblage associations as shown in the compiled data of Appendix
A. Other rare or uncommon phases which are of note, however, were not studied in depth are reported in section 2.2.2.
2.2.1 Bismite, bismoclite, bismutite, cannonite and riomarinaite
Bismite Bi2O3 as a mineral was first described in 1753, a definitive analysis was first reported in 1848 (Frondel, 1943). The single-crystal structure of bismite was
23 | P a g e reported by Sillén (1940) and refined by Malmros (1970). The Colavi mine in the
Machacamarca district, Cornelio Saavedra Province, Potosí Department, Bolivia is taken to be the type locality and bismite is reported in the vast majority of bismuth deposits around the world.
Two basic carbonates of bismuth are known, bismutite, Bi2O2CO3 (Figure 2.1), and a synthetic phase of composition Bi4O4CO3(OH)2 (Taylor et al., 1984). The stabilities of these phases are known (Clissold, 2007). Bismutite was first named by
Breithaupt (1841) using material from Ullersreuth, Vogtland, Germany. However, a single type locality cannot be definitely ascribed. Frondel (1943) reviewed the available evidence and concluded that the mineral had the composition Bi2O2CO3. The single crystal structure was originally reported by Lagerkrantz and Sillén (1948) and refined by Grice (2002). The predominance of bismutite amongst the vast majority of Bi-rich deposits consequently renders it the most common secondary Bi mineral. Bismite,
Bi2O3, is a rare phase by comparison and it should be noted again that Bi2O3 reacts with
CO2(g) under ambient conditions to give Bi2O2CO3 (Barreca et al., 2001).
The bismuth halide bismoclite, BiOCl, was first described from Jackal’s Water,
Steinkopf, Namaqualand, Northern Cape Province, South Africa, by Mountain (1937).
The structure was reported by Bannister (1935) and refined by Keramidas et al. (1993).
Bismoclite is commonly associated with bismutite, bismuthinite, jarosite, alunite, and cerussite.
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Figure 2.1: Bismutite from Schmiedestollen dump, Wittichen, Schenkenzell, Black Forest, Baden-Württemberg, Germany (Bonacina, 2011)
The minerals cannonite, Bi2(SO4)O(OH)2, (Figure 2.4) and riomarinaite
BiSO4(OH)·H2O form under typical secondary conditions. The structure of cannonite was reported by Golic et al. (1982), Sadanaga and Bunno (1974) first reported cannonite from the Ashio mine, Ashio, Tochigi Prefecture, Japan, where it was associated with native bismuth, bismuthinite, Bi sulfosalts, koechlinite, and zavaritskite.
However, a specimen from the Tunnel Extension No. 2 mine, Bullion Canyon, Piute
County, Utah, USA is taken to be the type locality (Stanley et al., 1992). The structure of riomarinaite, BiSO4(OH)·H2O, was reported by Graunar and Lazarini (1982).
According to Rögner (2005) riomarinaite was found at the Falcacci stope, Rio Marina mine, Elba Island, Tuscany, Italy and it was associated with primary phases including
25 | P a g e bismuth, bismuthinite, Bi sulfosalts and molybdenite and secondary minerals bismoclite, bismutite, cannonite and daubréeite.
Figure 2.2: Cannonite from the Duadello mine (Baitello mine), Palotto Valley (Palot Valley), Fraine, Pisogne, Camonica Valley, Brescia Province, Lombardy, Italy (Bonacina, 2009).
2.2.2 Rare and other bismuth oxide, carbonates, chloride, and sulfate minerals The structure for sphareobismoite was reported by Blower and Greaves (1988) from the Schmiedestollen mine, Wittichen, Baden-Württemberg, Germany which was the reported type locality (Walenta, 1995), where it was found to be the oxidation product of wittichenite and emplectite. Sphareobismoite is predominantly associated with bismutite and mixite. Other associated secondary Bi minerals include atelestite, beyerite, bismite, bismutoferrite, orthowalpurgite, preisingerite, rooseveltite and
26 | P a g e walpurgite (Walenta, 1992, 1995). Sphaerobismoite is a rare phase compared to bismutite, which was is found repeatedly in Nature.
The type locality of beyerite, Ca(BiO)2(CO3)2 is Schneeberg, Saxony, Germany, which was first reported by Frondel (1943) where it was associated with bismutite.
Reported as a carbonate of Bi and Ca, a definite formula was not confirmed until later investigations by Heinrich (1947). The single crystal structure is known, originally reported by Lagerkrantz and Sillén (1948) and later refined by Grice (2002).
Another Bi-halide, perite, PbBiO2Cl, is commonly associated with bismutite.
The orthorhombic, pseudotetragonal structure for perite was reported by Gillberg
(1960) space group Bmmb, a = 5.591, b = 5.431 and c = 12.200 Å. However, Bridge
(1976) reported that perite from Glen Florrie Station, Western Australia, was tetragonal
(a = 5.579(3) and c = 12.45(1) Å). Both orthorhombic and tetragonal forms are known synthetically (Deschanvres et al., 1970; Ketterer and Krämer, 1985; Lopatkin, 1987).
The minerals aiolosite, Na2(Na2Bi)(SO4)3Cl, campostriniite, Bi12.67O14(SO4)5, and leguernite, (Bi,Na)3(Na,K)4(SO4)6·H2O, have been reported as primary volcanic sublimates or as the reaction product of sublimates (Demartin et al., 2010; Demartin et al., 2013; Garavelli et al., 2013). As such, they have not been negated from the future consideration regarding secondary Bi mineralogy.
27 | P a g e
2.3 EXPERIMENTAL
2.3.1 Syntheses of cannonite and riomarinaite
Cannonite was synthesised by adding, H2SO4, (49.78 mL, 0.1067 M, AR ≥98%)
® to a flask containing Bi2O3 (0.51315 g, ReagentPlus 99.9%) and magnetically stirred
(500 rpm) at room temperature. After 1 hour the initially yellow powder changed colour to white, however the mixture was left to stir for a further 5 days. The solid was then collected at the pump on GF/F grade filter paper, rinsed with DI water and acetone, and sucked dry.
Riomarinaite was synthesised by mixing H2SO4 (49.78 mL, 1.067 M, AR
® ≥98%) in a flask containing Bi2O3 (0.5093 g, ReagentPlus 99.9%) and magnetically stirred (500 rpm). The mixture was again observed to change colour after 1 hour from yellow to white but was left to stir for 5 days. The precipitate was isolated as above.
Powder X-ray diffraction studies of the products were carried-out using a
Bruker D8 Advance diffractometer (Ni-filtered CuKα1 radiation, λ = 1.5406 Å, 40 kV and 30 mA). Traces were produced between 5-70o 2θ, with a step size of 0.02o and a rate of 1.2 o min–1. Diffraction Technology Data processing software (Eva) and JCPDS-
ICDD data base files were used to identify the phases produced.
28 | P a g e
2.3.2 Solubility Studies
Solubility studies were undertaken using sealed 250 cm3 conical QuickfitR flasks maintained at 25.0 0.2oC in a thermostatted water bath inside a controlled temperature room at the same temperature. Measurements of pH were made using a Radiometer
ION450 apparatus fitted with a combination electrode. The solubility studies were conducted by precipitation of the desired product following the synthetic procedures for cannonite and riomarinaite. Bismuth oxide (ca 0.5 g) was added to a series of seven
3 conical flasks containing 49.97 cm of standardised H2SO4; 0.1067 M for cannonite and
1.067 M for riomarinaite. The flasks were left for 10 weeks during which time the pH of a paired flask was monitored periodically until the pH of the test mixture remained stable. The solutions were filtered using GF/F grade filter paper and the filtrates collected in clean PET specimen jars. Dissolved Bi concentrations were determined using ICP-MS by a NATA-compliant commercial laboratory (mgt|LabMark
Environmental Testing Australia Pty Ltd).
29 | P a g e
2.4 RESULTS
2.4.1 Synthesis of cannonite and riomarinaite
High purity, single phase samples of cannonite and riomarinaite were obtained in quantitative yield from the synthesis and dissolution of cannonite as shown by powder X-ray diffraction. Unit cell parameters were refined in LAPOD (Langford,
1973) and values obtained were a = 7.690(2), b = 13.861(6) and c = 5.682(2) Å for cannonite and a = 6.023(2), b = 13.362(1) and c = 6.490(5) Å for riomarinaite which are in good agreement with those reported by Golic et al. (2007) and Graunar and
Lazarini (1982) respectively.
2.4.2 Solubility Studies
Equilibrium was achieved after 6 weeks for cannonite but not for riomarinaite,
X-ray diffraction examination of the original riomarianite samples after 2 weeks and 10 weeks in solution indicated the formation of cannonite. Further solubility studies of riomarinaite were not pursued due to the apparent metastability. The apparent metastability of riomarinaite in contact with its mother liquor is shown in the X-ray diffraction traces presented in Figures 2.3-2.5 below.
30 | P a g e
1200
1100
1000
900
800
700
600
Lin (Counts) Lin
500
400
300
200
100
0
5 10 20 30 40 50 60 70 2-Theta - Scale
Figure 2.3: Powder XRD trace of riomarinaitre with peak positions of the ‘type’ pattern from JCPDS-ICDD file 01-076-1103 (red).
34 | P a g e
430 420 410 400 390 380 370 360 350 340 330 320 310 300 290 280 270 260 250 240 230 220 210 200 Lin (Counts) Lin 190 180 170 160 150 140 130 120 110 100 90 80 70 60 50 40 30 20 10 0
6 10 20 30 40 50 60 70 80 2-Theta - Scale
Figure 2.4: Powder XRD trace of riomarinaite after 2 weeks showing a mixture of riomarinaite and cannonite with peak positions of the ‘type’
patterns from JCPDS-ICDD files for riomarinaite 01-076-1103 (red) and cannonite 00-045-1439 (blue).
35 | P a g e
600
500
400
300
Lin (Counts) Lin
200
100
0
6 10 20 30 40 50 60 70 2-Theta - Scale
Figure 2.5: Powder XRD trace of riomarinaite after 10 weeks converted to cannonite with peak positions of the ‘type’ pattern for
cannonite from JCPDS-ICDD file 00-045-1439.
36 | P a g e
Cannonite dissolved incongruently in aqueous H2SO4 as expressed in equation (1).
+ 2+ - Bi2(SO4)O(OH)2(s) + 3H (aq) ⇋ BiOH (aq) + H2O(l) + HSO4 (aq) (1)
Individual ion activity coefficients were calculated using the Debye-Hückel equation for 298.15 K, lg = –0.5085z2(I/(1+I). For cannonite I = 0.128 mol dm–3,
3 = 0.093 2 = 0.348 and = 0.768. In all instances, o is taken to be unity. The
+ + activity of H (aq), a(H ), in H2SO4(aq) (0.1084 M) was then calculated and corresponding activity a(Bi3+), was calculated from the solubility data (Table 2.1).
Table 2.1 Dissolved metal concentrations for cannonite
Solution [Bi] ppm [Bi] mol dm-3 1 22 1.053 x 10-4 2 21 1.000 x 10-4 3 23 1.101 x 10-4 4 21 1.000 x 10-4 5 21 1.000 x 10-4 6 21 1.000 x 10-4 Mean 21.50 1.028 x 10-4 Error ±1.4 ±2.05 x 10-5
The pH at equilibrium (1.047) was used in the determination of individual ion speciation using COMICS (Perrin and Sayce, 1967). Reliable lg K values for equation
(2), (4), (6), (8), (10), (12) and (14) of lg K(298.15 K) = –1.11, –3.30, –8.21, 2.01, 3.41,
4.60 and 4.88 at I = 0 mol dm–3 were reported by Fedorov et al. (1971) and van Der Lee
37 | P a g e and Lomenech (2004). Correction to I = 0.128, mol dm–3 by the method of Baes and
Mesmer (1976), yields lg K(298.15 K) = –1.73, –4.30 and –9.33. Using the relationships shown by equations (3), (5) and (7), (9), (11), (13) and (15), the
2+ + o -5 concentration of Bi(OH) (aq), Bi(OH)2 (aq) and Bi(OH)3 (aq) are 2.20 x 10 , 7.20 x
10-7 and 1.30 x 10-10 mol dm–3 respectively.
3+ 2+ + Bi (aq) + H2O(l) ⇋ Bi(OH) (aq) + H (aq) (2)
[Bi(OH)2+].[H+]/[Bi3+] = 10–1.11 (3)
3+ + + Bi (aq) + 2H2O(l) ⇋ Bi(OH)2 (aq) + 2H (aq) (4)
+ + 3+ –3.30 [Bi(OH)2 ].2[H ]/[Bi ] = 10 (5)
3+ 0 + Bi (aq) + 3H2O(l) ⇋ Bi(OH)3 (aq) + 3H (aq) (6)
0 + 3+ –8.21 [Bi(OH)3 ].3[H ]/[Bi ] = 10 (7)
3+ 2- + Bi (aq) + SO4 (aq) ⇋ BiSO4 (aq) (8)
+ 3+ 2 +2.01 [BiSO4 ]/[Bi ].[ SO4 ] = 10 (9)
3+ 2- - Bi (aq) + 2SO4 (aq) ⇋ Bi(SO4)2 (aq) (10)
+ 3+ 2 +3.51 [BiSO4 ]/[Bi ].2[ SO4 ] = 10 (11)
3+ 2- 3- Bi (aq) + 3SO4 (aq) ⇋ Bi(SO4)3 (aq) (12)
+ 3+ 2 +4.60 [BiSO4 ]/[Bi ].3[ SO4 ] = 10 (13)
3+ 2- 5- Bi (aq) + 4SO4 (aq) ⇋ Bi(SO4)4 (aq) (14)
+ 3+ 2 +4.88 [BiSO4 ]/[Bi ].4[ SO4 ] = 10 (15)
38 | P a g e
This yields a value of lg K for equation (1) –8.00 ± 0.50 and yields a
ө -1 corresponding value for ΔGr (298.15 K) = +45.68 kj.mol . Thus,
ө –1 ΔGf (Bi2(SO4)O(OH)2, s, 298.15 K) = –1315.98 ± 0.5 kJ mol The estimated error takes into account the analytical error of the solubility experiments and errors quoted for the thermochemical data used in Table 2.2.
Table 2.2 Thermodynamic quantities used in the calculations (T = 298.15 K).
ө -1 ΔGf /kJ mol Reference bismoclite –322.1 Kaye and Laby (1995) bismutitea –916.2 ± 7.5 see text cannonite –716.91 ± 0.5 this study
+ b BiSO4 (aq) –663.65 see text 2- b Bi(SO4) (aq) –1415.64 see text 3- b Bi(SO4)3 (aq) –2177.91 see text 5- b Bi(SO4)4 (aq) –2931.5 see text o c Bi(OH)3 (aq) –572.61 see text + c Bi(OH)2 (aq) –363.54 see text Bi(OH)2+(aq)c –138.94 see text Bi3+(aq)c +91.82 see text
CO2(g) –394 Robie and Hemingway (1995) Cl-(aq) –131.2± 0.1 Robie and Hemingway (1995)
H2O(l) –237.1± 0.1 Cox et al. (1989) a Values have been recalculated using values for H2O(l), CO2(g) and Bi2O3(s) at 298.2 K taken from Robie and Hemingway (1995).bCalculated using values from Fedorov et al. (1971) and dissociation constants of sulfuric acid from Martell and Smith (1982). cCalculated using standard electrode potentials from Lovreček et al. (1985) to determine o 3+ ΔGf (Bi ) and dissociation constants from van Der Lee and Lomenech (2004).
39 | P a g e
2.5 REFERENCES
Baes, C.F. Jr and Mesmer, R.E. (1976) The Hydrolysis of Cations. Plenum Press, New
York.
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.
Blower, S.K. and Greaves, C. (1988) The structure of β-Bi2O3 from powder neutron
diffraction data. Acta Crystallographica, C44, 587-589.
Bonacina, E., (2009) Cannonite: Bi2(SO4)O(OH)2 Duadello Mine (Baitello mine),
Palotto Valley (Palot Valley), Fraine, Pisogne, Camonica Valley, Brescia Province,
Lombardy, Italy, photograph, viewed 4 January 2013,
Bonacina, E., (2011) Bismutite : (BiO)2CO3 Schmiedestollen dump, Wittichen,
Schenkenzell, Black Forest, Baden-Württemberg, Germany, photograph, viewed 4
January 2013,
Breithaupt, A. (1841) Über das natürliche kohlensaure Wismutoxyd. Poggendorffs
Annalen der Physik und Chemie, 53, 627-630.
Clissold, M.E. (2007) Aspects of the supergene geochemistry of copper nickel and
bismuth. Unpublished PhD thesis, University of Western Sydney.
40 | P a g e
Cox, J.D., Wagman, D.D. and Medvedev, V.A. (1989) CODATA Key Values for
Thermodynamics. Hemisphere Press, New York.
Demartin, F., Gramaccioli, C.M., Campostrini, I. and Pilati, T. (2010) Aiolosite,
Na2(Na2Bi)(SO4)3Cl, a new sulfate isotypic to apatite from La Fossa Crater,
Vulcano, Aeolian Islands, Italy. American Mineralogist, 95, 382-385.
Demartin, F., Gramaccioli, C.M., Campostrini, I. and Pilati, T. (2013) Campostriniite,
IMA 2013-086, CNMNC Newsletter No.18, December 2013, page 3255 -
Mineralogical Magazine, 77, 3249- 3258.
Fedorov, V.A., Kalosh, T.N., Chernikova, G.E. and Mironov, V.E. (1971) Sulphato-
complexes of bismuth(III). Russian Journal of Physical Chemistry, 45, 106.
Frondel, C. (1943) Mineralogy of the oxides and carbonates of bismuth. American
Mineralogist, 28, 521-535.
Golic, L., Graunar, M. and Lazarini, F. (1982) Catena-di-μ-hydroxo-μ3-oxo-
dibismuth(III) sulfate. Acta Crystallographica, B38, 2881-2883.
Grice, J.D. (2002) A solution to the crystal structures of bismutite and beyerite.
Canadian Mineralogist, 40, 693-698.
41 | P a g e
Graunar, M. and Lazarini, F. (1982) Di-μ-hydroxo-bis[aquasulfatobismuth(III)]. Acta
Crystallographica, B38, 2879-2881.
Kaye, G.W.C. and Laby, T.H. (1995) Tables of Physical and Chemical Constants. 16th
Edition, Longman, London, Section 3.10.5.
Lagerkrantz, A. and Sillén, G. (1948) On the crystal structure of Bi2O2CO3 (bismutite)
and CaBi2O2(CO3)2 (beyerite). Arkiv för Kemi, Mineralogi och Geologi, 25, 1-21.
Langford, J.I. (1973) Least-squares refinement of cell dimensions from powder data by
Cohen's method. Journal of Applied Crystallography, 6, 190-196.
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.
Malmros, G. (1970) The crystal structure of α-Bi2O3. Acta Chemica Scandinavica, 24,
384-396.
Martell, A.E. and Smith, R.M. (1982) Critical Stability Constants. Volume 5:First
Supplement. Plenum Press, New York.
42 | P a g e
Mountain, E.D. (1937) Two new bismuth minerals from South Africa. Mineralogical
Magazine, 24, 59-64.
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.
Rögner, P. (2005) Riomarinait, ein neues Wismutmineral vom Abbau Falcacci, Rio
Marina, Elba (Italien). Aufschluss, 56, 53-60.
Sadanaga, R. and Bunno, M. (1974) The Wakabayashi Mineral Collection. Bulletin of
the University Museum, University of Tokyo, 7
Sillén, L. (1940) Die Kristallstruktur des monoklinen α-Bi2O3. Naturwissenschaften, 28,
206-207.
Stanley, C.J., A.C. Roberts, D.C. Harris, A.J. Criddle, and J.T. Szymański (1992)
Cannonite, Bi2O(OH)2SO4, a new mineral from Marysvale, Utah, USA.
Mineralogical Magazine, 56, 605-609.
Taylor, P., Sunder, S. and Lopata, V.J. (1984) Structure, spectra, and stability of solid
bismuth carbonates. Canadian Journal of Chemistry, 62, 2863-2873.
van der Lee, J. and Lomenech, C. (2004) Towards a common thermodynamic database
for speciation models. Radiochimica Acta, 92, 811-818.
43 | P a g e
Walenta, K. (1992) Die Mineralien des Schwarzwaldes. Weise, Munich.
Walenta, K. (1995) Sphaerobismoite, a new mineral of the composition Bi2O3 from the
Black Forest. Der Aufschluss, 46, 245-248.
44 | P a g e
CHAPTER 3
ROOSEVELTITE, PREISINGERITE AND ATELESTITE
45 | P a g e
3.1 ABSTRACT
Secondary Bi-As minerals play a role in determining the extent of Bi dispersion in the supergene environment. Syntheses and stability studies of atelestite,
Bi2(AsO4)O(OH), preisingerite, Bi3(AsO4)2O(OH), tetrarooseveltite, BiAsO4 and rooseveltite, BiAsO4 have been undertaken in order to elucidate their contribution to Bi immobilisation. Solubilities in aqueous HNO3 were determined at 298.2 K and the data
ө ө obtained used to calculate values of ΔGf at the same temperature. The derived ΔGf
(298.2 K) values for atelestite, (–1102.58 ± 5.6 kJ mol–1), preisingerite, (–1823.29 ± 2.5 kJ mol–1) and rooseveltite (–716.91 ± 1.5 kJ mol–1) have been used in subsequent calculations to determine their relative stabilities and relationships with other secondary
Bi minerals.
3.2 INTRODUCTION
The minerals atelestite, Bi2(AsO4)O(OH), preisingerite, Bi3(AsO4)2O(OH), tetrarooseveltite, BiAsO4 and rooseveltite, BiAsO4, have been reported from multiple localities worldwide (Chapter 2, Table 1) and are the most abundant of the Bi-As minerals found. Bismuth arsenates are rare minerals, but they can be a common feature of some bismuth geochemical settings which are discussed herein. Therefore, it is important to understand the role As plays in limiting the dispersion of Bi in the oxidising environment. In an Australian context, the minerals rooseveltite and preisingerite have been reported from the Elsmore mine, Elsmore, New South Wales,
Australia (Rankin et al., 2002, 2013), yet atelestite to date has never been reported.
Rooseveltite and preisingerite were found to be closely associated with bismoclite
(Rankin et al., 2013) at this locality. Bismuth and bismuthinite are primary phases.
46 | P a g e
Other secondary Bi minerals identified from Elsmore included bismite, bismutite,
“bismutostibiconite”, cannonite, russellite, sardignaite, waylandite and zavaritskite
(Rankin et al., 2002, 2013). This chapter has focused on the chemical modelling of bismuth arsenates the data presented cab be used to determine the roles theses phases play at different mine sites globally. As such the use of data from previous chapters can be included to draw conclusions on the dispersion of bismuth in the environment.
Atelestite (Figure 3.1) was first reported from the Neuhilfe mine, Schneeberg,
Saxony, Germany (Breithaupt, 1832). It is often associated with primary bismuth minerals and bismuth sulfosalts as well as secondary Bi minerals including, bismutite, bismutoferrite and paulkellerite (Breithaupt, 1832; Dunn et al., 1988; Weiss, 2007) mixite, preisingerite, rooseveltite and walpurgite (Palache et al., 1951; Walenta, 1972,
1992) and beyerite, bismite, orthowalpurgite and sphaerobismoite (Walenta, 1992,
1995a). The structure of atelestite was reported by Mereiter and Preisinger (1986).
Figure 3.1: 0.5 mm balls of yellow atelestite overgrowing spherules of bismutite. From Hérival, Val-d'Ajol, Vosges, Lorraine, France. (Valverde, 2006)
47 | P a g e
Both the structure and the mineral occurrence of preisingerite, Bi3(AsO4)2O(OH),
(Figure 3.2) were first reported from the San Francisco de los Andes, Calingasta, San
Juan, Argentina (Bedlivy and Mereiter, 1982b) where it was found to be associated with bismuth, bismuthinite, Bi sulfosalts and rooseveltite (Bedlivy et al., 1972; Bedlivy and
Mereiter, 1982b). Other secondary Bi mineral associations reported with preisingerite include beyerite, bismutite, pucherite and walpurgite (Schlegel et al., 1996), neustädtelite (Meier and Dünkel, 2010), bismutite, bismutoferrite and neustädtelite
(Meier and Dünkel, 2010), as well as atelestite, bismite, bismoclite, bismutoferrite, mixite, rooseveltite and walpurgite (Markl, 1990; Walenta, 1992).
Figure 3.2: Preisingerite from the Clara Mine, Rankach valley, Oberwolfach, Wolfach, Black Forest, Baden-Württemberg, Germany, picture width 2 mm (Wolfsried, 2007).
Rooseveltite, BiAsO4, (Figure 3.3) was first described by Herzenberg (1946) whereby the specimen analysed was from the Santiaguillo, Macha, Chayanta Province,
Potosí Department, Bolivia (Herzenberg, 1946), but interestingly no other Bi minerals have been reported from this site. Rooseveltite’s structure was first reported by Bedlivy
48 | P a g e and Mereiter (1982a). Rooseveltite has had few reported localities (Anthony et al.,
2000) and, as mentioned previously, was reported from Australia at the Elsmore mine,
NSW.
Figure 3.3 : Rooseveltite aggregates (white to pale yellow: ~1mm) and marcasite,FeS2, (metallic green) from the Lagoa Mine, Estorãos, Ponte de Lima, Viana do Castelo District, Portugal (Alves, 2010).
Tetrarooseveltite, BiAsO4, has a known structure (Mooney, 1948). The type locality and only known specimen reported to date is the Moldava deposit, Krušnéhory
Mountains, Bohemia, Czech Republic. The specimen was associated with bayldonite, malachite, and mimetite in a fluorite-barite-quartz vein (Sejkora and Řídkošil, 1994); primary Bi phases are bismuth, bismuthinite and Bi sulfosalts; other secondary minerals are bismutite, mixite, preisingerite, rooseveltite and zavaritskite (Sejkora, 1994; Sejkora and Řídkošil, 1994).
49 | P a g e
3.3 EXPERIMENTAL
3.3.1 Syntheses
Rooseveltite was synthesised by mixing arsenic acid (50mL, 0.1 M) with riomarinaite (0.5 g) in an acid digestion bomb, which was sealed and heated at 180oC for three days. The mixture was allowed to cool to ambient temperature in the bomb.
The obtained solid was then collected at the pump on GF/F grade filter paper, rinsed with DI water and acetone, and sucked dry.
® Atelestite was synthesised by adding Bi2O3 (0.5013 g, ReagentPlus 99.9%) and
Na2HAsO4∙7H2O (0.5001 g, ≥98%), mixed in an acid digestion bomb with deionised water (50 mL). The mixture was buffered to pH 4.39 with 2 M KOH. The bomb was then placed in an oven (190oC) for eleven days. The bomb was removed and allowed to cool to ambient temperature and the product was collected as above.
Preisingerite was synthesised by mixing arsenic acid (100.00 mL, 0.1 M) to a round bottomed flask containing riomarinaite (0.5 g). The mixture was then refluxed for
48 hours and the product was isolated as above.
Powder X-ray diffraction studies of the products were carried-out using a
Philips PW1825/20 powder diffractometer (Ni-filtered CuKα1 radiation, λ = 1.5406 Å,
40 kV, 30 mA). Traces were produced between 5-70o 2θ, with a step size of 0.02 o and a rate of 1.2 o min–1. Diffraction Technology Data processing software (Traces Version 6) and JCPDS-ICDD data base files were used to identify the phases produced.
50 | P a g e
3.3.2 Solubility Studies
Solubility studies were undertaken using sealed 250 cm3 conical QuickfitR flasks maintained at 25.0 0.2oC in a thermostatted water bath inside a controlled temperature room at the same temperature. Measurements of pH were made using a Radiometer
ION450 apparatus fitted with a combination electrode. The minerals (ca 0.1 g) were
3 added to a series of conical flasks containing 100 cm of standardised HNO3; 0.0981 M.
The flasks were left for 10 weeks during which time the pH of a paired flask was monitored periodically until no change was detected. The remaining solutions were collected by filtration through WhatmanR GF/F fibreglass filter papers and stored in clean PET bottles. Dissolved Bi/As concentrations were determined using ICP-MS by a
NATA-compliant commercial laboratory (mgt | LabMark Environmental Testing
Australia Pty Ltd).
3.4 RESULTS
3.4.1 Syntheses of rooseveltite, tetrarooseveltite, atelestite and preisingerite
High purity samples of atelestite, preisingerite and rooseveltite were obtained in an essentially quantitative yield. Powder X-ray diffraction did not give any evidence for any contaminating phase. Unit cell parameters were refined using the program LAPOD
(Langford, 1973), based on indices calculated using PowderCell (Kraus and Nolze,
1996a,b) and gave a = 6.878(1), b =7.159 (2) c =6.734(3) Å for rooseveltite, a = 9.993
(1), 7.404 (1) c = 6.937 (3) Å for preisingerite, and a = 7.000 (1), 7.430(1) c = 10.831
(2) Å for atelestite. These results are in excellent agreement with those reported elsewhere (Bedlivy and Mereiter, 1982a, 1982b; Mereiter and Preisinger, 1986).
51 | P a g e
120
110
100
90
80
70
60
Lin (Counts) Lin
50
40
30
20
10
0
9 10 20 30 40 50 60 2-Theta - Scale Figure 3.4: Powder XRD trace of rooseveltite with peak positions of the ‘type’ pattern from JCPDS file 00-025-0089 (red).
52 | P a g e
280
270
260
250
240
230
220
210
200
190
180
170
160
150
140
130
Lin (Counts) Lin 120
110
100
90
80
70
60
50
40
30
20
10
0
10 20 30 40 50 2-Theta - Scale Figure 3.5: Powder XRD trace of preisingerite with peak positions of the ‘type’ pattern from JCPDS file 01-075-1629 (red).
53 | P a g e
120
110
100
90
80
70
60
Lin (Counts) Lin 50
40
30
20
10
0
11 20 30 40 50 60 70 2-Theta - Scale Figure 3.6: Powder XRD trace of atelestite with peak positions of the ‘type’ pattern from JCPDS file 00-025-0089 (red).
54 | P a g e
3.4.2 Solution studies
Solubility data for the three minerals are reported in Tables 3.1, 3.2 and 3.3. All three phases are comparatively insoluble. Rooseveltite and preisingerite dissolve congruently and atelestite dissolved incongruently in aqueous HNO3. The incongruent dissolution of atelestite was accounted for with respect to preisingerite. The dissolution of the minerals is expressed in equations (1), (2) and (3).
+ 3+ BiAsO4 (s) + 2H (aq) ⇋ Bi (aq) + H2AsO4 (aq) (1)
+ 3+ - Bi3(AsO4)2O(OH)(s) + 7H (aq) ⇋ 3Bi (aq) + 2H2O(l) + 2HAsO4 (aq) (2)
+ 3+ 0 Bi2(AsO4)O(OH)(s) + 6H (aq) ⇋ 2Bi (aq) + 2H2O(l) + H3AsO4 (aq) (3)
The pH at equilibrium (rooseveltite = 1.210, preisingerite =1.080 ; and atelestite
= 1.152,) was used in the determination of ion speciation patterns using the program
COMICS (Perrin and Sayce, 1967). Individual ion activity coefficients were calculated using the Debye-Hückel equation for 298.15 K, lg = –0.5085z2((I/(1+I)-0.3I). For rooseveltite I = 0.098 mol.dm–3, 3 = 0.081, 2 = 0.327 and = 0.756. For preisingerite I = 0.090 mol.dm–3, 3 = 0.043, 2 = 0.246 and = 0.704 and for atelestite I = 0.102 mol.dm–3, 3 = 0.1079, 2 = 0.372 and = 0.781. In all instances,
o + + is taken to be unity. The activity of H (aq), a(H ), in HNO3 0.0981 M was then calculated and corresponding activity a(Bi3+) was calculated from the solubility data
(Tables 3.1, 3.2 and 3.3).
55 | P a g e
Table 3.1 Dissolved metal concentrations for rooseveltite
Solution [Bi] ppm [Bi] mol dm-3 [As] ppm [As] mol dm-3 1 0.41 1.96 x 10-06 0.91 9.49 x 10-06 2 0.35 1.67 x 10-06 0.72 7.50 x 10-06 3 0.41 1.96 x 10-06 0.76 7.92 x 10-06 4 0.36 1.72 x 10-06 0.80 8.34 x 10-06 5 0.35 1.67 x 10-06 0.75 7.82 x 10-06 6 0.43 2.06 x 10-06 0.71 7.40 x 10-06 7 0.34 1.63 x 10-06 0.78 8.13 x 10-06 8 0.36 1.72 x 10-06 0.86 8.96 x 10-06 9 0.34 1.63 x 10-06 0.76 7.92 x 10-06 Mean 0.36 1.73 x 10-06 0.85 8.08 x 10-06 Error 0.03 1.52 x 10-07 0.05 5.56 x 10-07
Table 3.2. Dissolved metal concentrations for preisingerite
Solution [Bi] ppm [Bi] mol dm-3 [As] ppm [As] mol dm-3 1 0.59 2.8 x 10-06 1.8 2.4 x 10-05 2 0.52 2.5 x 10-06 2.1 2.8 x 10-05 3 0.58 2.8 x 10-06 1.9 2.5 x 10-05 4 0.61 2.9 x 10-06 1.7 2.3 x 10-05 5 0.37 1.8 x 10-06 3.1 4.1 x 10-05 Mean 0.46 2.2 x 10-06 2.1 2.8 x 10-05 Error 0.16 7.4 x 10-07 2.7 1.3 x 10-05
Table 3.3. Dissolved metal concentrations for atelestite
Solution [Bi] ppm [Bi] mol dm-3 1 150 7.2 x 10-04 2 160 7.7 x 10-04 3 170 8.1 x 10-04 4 180 8.6 x 10-04 5 160 7.7 x 10-04 6 150 7.2 x 10-04 Mean 162 7.7 x 10-04 Error 8.89 4.25 x 10-05
56 | P a g e
The pH at equilibrium for rooseveltite was used in the determination of individual ion speciation using COMICS (Perrin and Sayce, 1967). Reliable Log K values for equation (2), (4), (6), (8), (10), (12) and (14) of Log K(298.15 K) = –1.34, –
3.52, -8.44, +10.62, +17.75 and +19.48 at I = 0 mol dm–3 were reported by van Der Lee and Lomenech (2004) and Wagman et al. (1982). Correction to I = 0.128, mol dm–3 by the method of Baes and Mesmer (1976), yields lg K(298.15 K) = -1.54, –4.05, –9.07,
10.96, 17.29 and 19.52 Using the relationships shown by equations (5), (7), (9), (11),
2+ + o (13), and (15) the concentrations of Bi(OH) (aq), Bi(OH)2 (aq), Bi(OH)3 (aq),
2 - 2- -7 -8 -12 -6 HAsO4 (aq), and H2AsO4 (aq) are 7.10 x 10 , 7.60 x 10 , 2.3 x 10 , 1.9 x 10 , 6.2 x
10-6 mol.dm–3 respectively.
3+ 2+ + Bi (aq) + H2O(l) ⇋ Bi(OH) (aq) + H (aq) (4)
[Bi(OH)2+].[H+]/[Bi3+] = 10–1.11 (5)
3+ + + Bi (aq) + 2H2O(l) ⇋ Bi(OH)2 (aq) + 2H (aq) (6)
+ + 3+ –3.30 [Bi(OH)2 ].2[H ]/[Bi ] = 10 (7)
3+ 0 + Bi (aq) + 3H2O(l) ⇋ Bi(OH)3 (aq) + 3H (aq) (8)
0 + 3+ –8.21 [Bi(OH)3 ].3[H ]/[Bi ] = 10 (9)
3- + - AsO4 (aq) + H (aq) ⇋ HAsO4 (aq) (10)
- 3- +11.60 [HAsO4 ]/[ AsO4 ] = 10 (11)
3- + 2- AsO4 (aq) + 2H (aq) ⇋ H2AsO4 (aq) (12)
2- 3- +18.36 [H2AsO4 ]/[ AsO4 ] = 10 (13)
3- + 0 AsO4 (aq) + 3H (aq) ⇋ H3AsO4 (aq) (14)
2- 3- +20.81 [H3AsO4 ]/[ AsO4 ] = 10 (15)
57 | P a g e
Correction to I = 0.128, mol.dm–3 for preisingerite by the method of Baes and
Mesmer (1976), yields lg K(298.15 K) = –1.54, –3.94, –8.85, +10.96, 17.29 and 19.52.
Using the relationships shown by equations (5), (7), (9), (11), (13), and (15) the
2+ + o 2 - 2- concentration of Bi(OH) (aq), Bi(OH)2 (aq), Bi(OH)3 (aq), HAsO4 (aq), H2AsO4 (aq)
0 -8 -9 -9 -6 -12 and H3AsO4 (aq) are 6.60 x 10 , 5.10 x 10 7.53 x 10 , 1.20 x 10 , 2.8 x 10 , and
4.10 x 10-18, mol dm–3 respectively.
Correction to I = 0.128, mol.dm–3 for atelestite by the method of Baes and
Mesmer (1976), yields lg K(298.15 K) = –1.54, –4.05, –9.07, 10.96, 17.29 and 19.52.
Using the relationships shown by equations (5), (7), (9), (11), (13), and (15) the
2+ + o 2 - 2- concentration of Bi(OH) (aq), Bi(OH)2 (aq), Bi(OH)3 (aq), HAsO4 (aq), H2AsO4 (aq)
0 -5 -7 -10 –3 and H3AsO4 (aq) are 2.20 x 10 , 7.20 x 10 and 1.30 x 10 mol.dm respectively. the
2+ + o -5 concentration of Bi(OH) (aq), Bi(OH)2 (aq) and Bi(OH)3 (aq) are 2.20 x 10 , 7.20 x
10-7 and 1.30 x 10-10 mol.dm–3 respectively.
This yields values of lg K for the dissolution of rooseveltite, preisingerite and atelestite for equations (1) –9.65±0.50, (2) –41.43±0.50, and (3) –7.93±0.50
ө ө respectively and yields the corresponding ΔGr and ΔGf values for equations (1) to (3) as follows:
ө ө (1) ΔGr (298.15 K) = +55.08. Thus, ΔGf (BiAsO4, 298.15 K) = –
716.91±1.5 kJ mol–1
ө ө (2) ΔGr (298.15 K) = +7.26. Thus, ΔGf (Bi3(AsO4)2O(OH), 298.15 K) =
–1823.29 ±2.5 kJ mol–11
ө ө (3) ΔGr (298.15 K) = +45.27. Thus, ΔGf Bi2(AsO4)O(OH), 298.15 K) =
–1102.58 ±5.6 kJ mol–1
58 | P a g e
The estimated error takes into account the analytical error of the solubility experiments and errors quoted for the thermochemical data used.
Table 3.4 Thermodynamic quantities used in the calculations (T = 298.15 K).
ө -1 ΔGf /kJ mol Reference bismoclite –322.1 Kaye and Laby (1995) bismutitea –916.2 ± 7.5 see text rooseveltite –716.91 ± 0.5 this study preisingerite –1823.29 ± 0.5 this study atelestite –1102.58 ± 0.5 this study
o H3AsO4 (aq) –766.75 Nordstrom and Archer (2003) - H2AsO4 (aq) –753.65 Nordstrom and Archer (2003) 2- HAsO4 (aq) –713.73 Nordstrom and Archer (2003) 3- b AsO4 (aq) –646.36 see text o c Bi(OH)3 (aq) –572.61 see text + c Bi(OH)2 (aq) –363.54 see text Bi(OH)2+(aq)c –138.94 see text Bi3+(aq)c +91.82 see text
CO2(g) –394 Robie and Hemingway (1995) Cl-(aq) –131.2 ± 0.1 Robie and Hemingway (1995)
H2O(l) –237.1 ± 0.1 Cox et al. (1989) a Values have been recalculated using values for H2O(l), CO2(g) and Bi2O3(s) at 298.2 K b ө 3- taken from Robie and Hemingway (1995). Calculated using ΔGf (AsO4 ) from Barner and Scheuerman (1978) and dissociation constants of arsenic acid from Martell and Smith (1982). cCalculated using standard electrode potentials from Lovrecek et al. ө 3+ (1985) to determine ΔGf (Bi ) and dissociation constants from van Der Lee and Lomenech (2004).
59 | P a g e
3.5 REFERENCES
Alves, P., (2010) Rooseveltite: Bi(AsO4), Marcasite: FeS2, Lagoa Mine, Estorãos, Ponte
de Lima, Viana do Castelo District, Portugal, photograph, viewed 4 January 2013,
http://www.mindat.org/photo-319350.html.
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.
Baes, C.F. Jr and Mesmer, R.E. (1976) The Hydrolysis of Cations. Plenum Press, New
York.
Barner, H. E. And Scheuerman, R. H. (1978) Handbook of thermochemical data for
compounds and aqueous species. John Wiley and Sons, New York.
Bedlivy, D., Llamblas, E.J. and Astarloa, J.F.H. (1972) Rooseveltit von San Francisco
de los Andes und Cerro Negro de la Aguadita, San Juan, Argentina. Tschermaks
Mineralogische und Petrographische Mitteilungen, 17, 65-75.
Bedlivy, D. and Mereiter, K. (1982a) Structure of α-BiAsO4 (rooseveltite). Acta
Crystallographica, 38, 1559-1561.
Bedlivy, D. and Mereiter, K. (1982b) Preisingerite, Bi3O(OH)(AsO4)2, a new species
from San Juan Province, Argentina: its description and crystal structure. American
Mineralogist, 67, 833-840.
60 | P a g e
Breithaupt, A. (1832) Vollständige Characteristik des Minerals-Systems, Second
edition. Arnoldische Buchhandlung, Dresden, p. 307.
Cox, J.D., Wagman, D.D. and Medvedev, V.A. (1989) CODATA Key Values for
Thermodynamics. Hemisphere Press, New York.
Dunn, P.J., Grice, J.D., Wicks, F.J. and Gault, R.A. (1988) Paulkellerite, a new bismuth
iron phosphate mineral from Schneeberg, Germany. American Mineralogist, 73,
870-872.
Herzenberg, R. (1946) Nuevos minerales de Bolivia. Boletín Técnico de la Técnico
Facultad Nacional Ingeniería, Universidad Técnica Oruro, 1, 10.
Kaye, G.W.C. and Laby, T.H. (1995) Tables of Physical and Chemical Constants. 16th
Edition, Longman, London, Section 3.10.5.
Kraus, W. and Nolze, G. (1996a) 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.
Kraus, W. and Nolze, G. (1996b) PowderCell 1.8 and Windows version 1.0. Federal
Institute for Materials Research and Testing (BAM), Berlin.
61 | P a g e
Langford, J.I. (1973) Least-squares refinement of cell dimensions from powder data by
Cohen's method. Journal of Applied Crystallography, 6, 190-196.
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.
Markl, G. (1990) Mineralogie der Grube Anton bei Schiltach im Heubachtal,
Schwarzwald. Lapis, 15(5), 11-20, 50.
Martell , A. E. and Smith, R. M. (1982) Critical Stability Constants Volume 5: First
Supplement. Plenum Press, New York.
Meier, S. and Dünkel, B. (2010) Mineralien von der Dorschenmühle bei Lichtenberg,
Franken. Lapis, 35(10), 60-64, 90.
Mereiter, K. and Preisinger, A. (1986) Kristallstrukturdaten der Wismutminerale
Atelestit, Mixit und Pucherit. Anzeiger Österreichischen Akademie der
Wissenschaften mathematisch - naturwissenschaftlichen Klasse, 123, 79-81.
Mooney, R.C.L. (1948) Crystal structure of tetragonal bismuth arsenate. Acta
Crystallographica, 1, 163-165.
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Nordstrom, D.K. and Archer, D.G. (2003) Arsenic thermodynamic data and
environmental geochemistry. In Welch, A.H. and Stollenwerk, K.G. (Eds) Arsenic
in Ground Water. Kluwer Academic Publishers, Boston, pp. 1-25.
Palache, C., Berman, H. and Frondel, C. (1951) Dana’s System of Mineralogy, seventh
edition. John Wiley and Sons, New York.
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.
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.
Rankin, J., Sharpe, J.L. and Williams, P.A. (2013) Unpublished survey of secondary Bi,
Mo and W minerals in Australian deposits.
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.
Schlegel, L., Kleeberg, R. and Meisser, N. (1996) Sekundäre Wismutminerale und
weitere Neufunde aus Schneeberg/Sachsen, 1992-1995. Lapis, 21(9), 37-41.
63 | P a g e
Sejkora, J. (1994) Minerály ložiska Moldava v Krušných horách. Bulletin
Mineralogicko-petrografického oddělení Národního muzea v Praze, 2, 110-116.
Sejkora, J. and Řídkošil, T. (1994) Tetrarooseveltite, Bi(AsO4), a new mineral species
from Moldava deposit, the Krušnéhory Mountains, northwestern Bohemia, Czech
Republic. Neues Jahrbuch für Mineralogie, Monatshefte, 179-184.
Valverde, J., (2006) Atelestite:Bi2(AsO4)O(OH) Hérival, Val-d'Ajol,
Vosges, Lorraine, France, photograph, viewed 4 January 2013,
http://www.mindat.org/photo-50845.html.
van der Lee, J. and Lomenech, C. (2004) Towards a common thermodynamic database
for speciation models. Radiochimica Acta, 92, 811-818.
Wagman, D. D., Evans, W. H., Parker, V. B, Schumm, R. H., Halow, I., Bailey, S.
M., Churney, K. L., and Nuttall, R. L. (1982) The NBS tables of chemical
thermodynamic properties: selected values for inorganic and C1 and C2 organic
substances in SI units. Journal of Physical and Chemical Reference Data, 11,
Supplement 2, 1-392.
Walenta, K., (1972) Die Sekundärmineralien der Co-Ni-Ag-Bi-U-Erzgänge im Gebiet
von Wittichen im mittleren Schwarzwald. Aufschluss, 23, 279-329.
Walenta, K., (1992) Die Mineralien des Schwarzwaldes. Weise, Munich
64 | P a g e
Walenta, K., (1995) Sphaerobismoite, a new mineral of the composition Bi2O3 from the
Black Forest. Der Aufschluss, 46, 245-248.
Weiss, S., Green, D.H., Hooper, J.J., and Elton, N. (2007) Erzgänge und “Alpine”
Klüfte: Die Mineralien des Hingston quarry, Calstock, Cornwall. Lapis, 32(11), 13-
25.
Wolfsried, S., (2007) Preisingerite:Bi3(AsO4)2O(OH) Clara Mine, Rankach valley,
Oberwolfach, Wolfach, Black Forest, Baden-Württemberg Germany, photograph,
viewed 4 January 2013, http://www.mindat.org/photo-102499.html.
65 | P a g e
CHAPTER 4
RUSSELLITE, KOECHLINITE AND SARDIGNAITE
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4.1 ABSTRACT
Bismuth is concentrated in a wide variety of ore types, principally associated with high-temperature acid intrusives, related skarn deposits and epithermal systems
(Angio 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
(Angio and Long, 1979; Baker et al., 2005). The association of Bi minerals at the Mo-
Bi deposits of Kingsgate and surrounding deposits found in the New England Orogen,
New South Wales, commonly give rise to koechlinite, Bi2MoO6, and russellite,
Bi2WO6, in the oxidised zone (Rankin et al., 2002; Sharpe and Williams, 2004;
Clissold, 2007). The Gibbs free energy of formation values for russellite, koechlinite,
ө and sardignaite, BiMo2O7(OH)∙2H2O, are derived in this chapter ΔGf (298.15 K) = –
1318.93±1.5 kJ mol–1, –1270.78±1.5 kJ mol–1 and –2176.94±1.56 kJ mol–1 respectively and are used to determine the roles they play in the immobilisation of bismuth in the oxidised environment.
4.2 INTRODUCTION
Molybdenum possesses exotic supergene mineralogy. Thirty different species are currently recognised by the IMA and most of them are rare mineral phases (Anthony et al., 1990, 1995, 1997, 2000, 2003; Gaines et al., 1997). The molybdate salts powellite, CaMoO4, and wulfenite, PbMoO4, are the most common, and have been both reported in small amounts 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 molybdite,
MoO3, and sidwillite, MoO3·2H2O, are very rare. This study has recognised that much material identified in the past as molybdite, or ferrimolybdite, Fe2(MoO4)·8H2O is in
67 | P a g e fact more often koechlinite Bi2MoO6. 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 bamfordite is known only from its type locality, the Bamford Hill W-Mo-Bi deposit, Bamford,
Tablelands Region, Queensland, Australia (Birch et al., 1998). These observations, together with knowledge of the occurrence of polymolybdate species, are important geochemical clues with respect to the dispersion of Mo in the supergene zone.
2- Like tungstate (VI), molybdate, MoO4 , polymerises under acid conditions if sufficiently high concentrations are reached (Baes and Mesmer, 1976) and molybdate can be dispersed under basic conditions in ground waters. However, when molybdenite oxidises together with bismuth or tungsten minerals, the very insoluble Aurivillius phases koechlinite, Bi2MoO6, and russellite, Bi2WO6, are formed. 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” have been shown to be koechlinite, Bi2MoO6. 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.
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
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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 micro-environments 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 (1).
2- 2- + MoS2(s) + 4O2(g) + 4H2O(l) → MoO4 (aq) + 2SO4 (aq) + 8H (aq) (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 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
2- pipes. In related deposits, such as at Elsmore, acid-catalysed polymerisation of MoO4 gives rise to Ca-Mg 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.
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The structure of koechlinite, Bi2MoO6, was originally reported by Zemann
(1956). This was subsequently refined by van den Elzen and Rieck (1973) and Teller et al. (1984). The type specimen was from St Daniel mine, Neustädtel, Schneeberg
District, Saxony, Germany (Schaller, 1916), where it was discovered in a quartz vein with bismuth and smaltite. Associated primary minerals include bismuthinite and secondary minerals include bismutite, preisingerite and neustädtelite (Wittern, 2001).
Another report on koechlinite (Yang et al., 1989), coated by chiluite occurs at an unnamed molybdenite deposit at Chilu, Fujian, China. Molybdenite, bismuthinite, joseite and cassiterite are present in the associated primary assemblage. In an Australian context, koechlinite is also common in various sites of the New England region, NSW,
Australia as mentioned in Chapter 1.
Figure 4.1: Koechlinite completely replacing bismuthinite needles, FOV 10mm. From Quartz vein outcrops, Knöttel area (Knötel; Knödel; Knödlberg), Krupka
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(Graupen), Krušné Hory Mts (Erzgebirge), Ústí Region, Bohemia (Böhmen; Boehmen), Czech Republic (Fuchs, 2012).
The structure of sardignaite, BiMo2O7(OH)·2H2O, was reported by Orlandi et al.
(2010) on the type specimen from Punta de Su Seinargiu, Sarroch, Cagliari Province,
Sardinia, Italy (Orlandi et al., 2010), at this site bismuth and molybdenite are primary phases; and sardignaite was associated with gelosaite. Another reported occurrence is from Elsmore Hill, Elsmore, associated with a host of secondary Bi and Mo minerals, particularly koechlinite (Rankin et al., 2013, unpublished data).
Figure 4.2: Elongated tabular crystals of sardignaite on quartz, with colourless fluorite group size crystals 1mm. from Punta de Su Seinargiu, Sarroch, Cagliari Province, Sardinia, Italy (Ambrino, 2013).
6+ 5+ Gelosaite, BiMo (2-5x)Mo 6xO7(OH)·H2O, was first reported by Orlandi et al
(2011) along with its structure. The type locality was the Punta de Su Seinargiu,
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Sarroch, Cagliari Province, Sardinia, Italy (Orlandi et al., 2011), where bismuth and molybdenite are primary phases and it was associated with sardignaite. In the same report (Orlandi et al., 2011) another occurrence is mentioned from the number 25 Pipe,
Kingsgate, New South Wales, Australia where it was associated with a host of secondary Mo and Bi minerals, and intimate associates are bismutite and bismite, but it usually occurs alone in vughs in quartz (Orlandi et al., 2011).
Figure 4.3: Cluster of gelosaite crystals 2mm across. Colour varies from greyish green to deep blue-green. from Old 25 Pipe, Kingsgate, Gough Co., New South Wales, Australia (Haupt, 2011)
The structure of russellite, Bi2WO6, (Figure 4.4) was re-determined from a neutron powder diffraction study of synthetic Bi2WO6 and reported by Knight (1992).
The type locality is Castle-an-Dinas mine, Castle-an-Dinas, St Columb Major,
Cornwall, UK, where wolframite is listed as a primary phase and chrysocolla is the only reported secondary phase (Hey and Bannister, 1938) .
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Figure 4.4: Yellow microcrystalline masses of russellite in cavities in quartz vein. Specimen size is 9.5x6x3 cm from Kara-Oba W deposit, Betpakdal Desert (Bet-Pak-Dal Desert), Karagandy Province (Qaragandy Oblysy; Karaganda Oblast'), Kazakhstan (Pavel, 2008)
4.3 EXPERIMENTAL
4.3.1 Syntheses of russellite, koechlinite and sardignaite
Russellite was obtained as follows. A mixture of Bi(NO3)3∙5H2O (1.0045 g,
ACS reagent ≥ 98%), Na2WO4∙2H2O (0.3564 g, ACS reagent ≥ 98%) and HNO3 (10 cm3, 0.1 M, ACS reagent 70%) was reacted in an acid digestion bomb at 180oC for 48 hours. The product obtained was a pale yellow, crystalline powder. The product was suspended in aqueous 0.1 M HNO3 at room temperature for 24 hours to dissolve any residual starting materials. It was then collected at the pump, washed with water then acetone, and vacuum dried.
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Koechlinite was synthesised in a similar way. A mixture of Bi(NO3)3∙5H2O
(1.0054 g, ACS reagent ≥ 98%), (NH4)6Mo7O24∙4H2O (0.18274 g, ACS reagent ≥ 98%)
3 and HNO3 (10 cm , 0.1 M, ACS reagent 70%) was reacted in an acid digestion bomb at
180oC for 48 hours. The colour of the crystalline powder obtained was off-white to yellow, and was isolated as described above.
Sardignaite was prepared by mixing Bi(NO3)3∙5H2O (0.5001 g),
3 (NH4)6Mo7O24∙4H2O (0.1999 g,) and HNO3 (20 cm , 0.1 M, ACS reagent 70%). The mixture was placed in an acid digestion bomb at 180oC for 48 hours. The product obtained was off-white in colour, and a crystalline powder was isolated as described above.
Powder X-ray diffraction studies of the products were carried-out using a Philips
PW1825/20 powder diffractometer (Ni-filtered CuKα1 radiation, λ = 1.5406 Å, 40 kV,
30 mA). Traces were produced between 5-70o 2θ, with a step size of 0.02 o and a rate of
1.2 o min–1. Diffraction Technology Data processing software (Traces Version 6) and
JCPDS-ICDD data base files were used to identify the phases produced.
4.3.2 Solubility studies
Solubility studies were undertaken using sealed 250 cm3 conical QuickfitR flasks maintained at 25.0 0.2oC in a thermostatted water bath inside a controlled temperature room at the same temperature. Measurements of pH were made using a Radiometer
ION450 apparatus fitted with a combination electrode. Subsequent analyses showed that all three minerals dissolve congruently in aqueous HNO3. The minerals (ca 0.1 g) were
3 added to a series of conical flasks containing 100 cm of standardised HNO3; 0.09928
M for koechlinite and russellite and 0.0981 M for sardignaite. The flasks were left for
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10 weeks, during which time the pH of paired flasks was monitored periodically until no change was detected. In all cases, equilibrium was achieved after 6 weeks. Resulting solutions were filtered through a WhatmanR GF/F fibreglass filter and collected in clean
PET bottles. Dissolved Bi/Mo and Bi/W concentrations were determined using ICP-MS by a NATA-compliant commercial laboratory (mgt | LabMark Environmental Testing
Australia Pty Ltd).
4.4 RESULTS
4.4.1 Syntheses of russellite, koechlinite and sardignaite
High purity, samples of russellite, koechlinite and sardignaite were obtained in essentially quantitative yield. Powder X-ray diffraction did not give any evidence for any contaminating phase. Unit cell parameters were refined using the program LAPOD
(Langford, 1973) and gave a = 5.439(2), b = 16.422(2), c = 5.45338) Å for russellite, a
= 5.493(3), b = 16.200(6) c = 5.507(3) Å for koechlinite, and a = 5.794(7), b = 11.56(2) c = 6.357(7) Å for sardignaite. These results are in excellent agreement with those reported elsewhere (Teller et al., 1984; Knight, 1992; and Orlandi et al., 2010).
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140
130
120
110
100
90
80
70
Lin (Counts) Lin
60
50
40
30
20
10
0
11 20 30 40 50 60 2-Theta - Scale
Figure 4.5: Powder XRD trace of russellite with peak positions of the ‘type’ pattern from JCPDS file 00-039-0256 (red).
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220
210
200
190
180
170
160
150
140
130
120
110
100
Lin (Counts) Lin
90
80
70
60
50
40
30
20
10
0
5 10 20 30 40 50 60 70 2-Theta - Scale
Figure 4.6: Powder XRD trace of koechlinite with peak positions of the ‘type’ pattern from JCPDS file 01-072-1524 (red).
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160
150
140
130
120
110
100
90
80
Lin (Counts) Lin 70
60
50
40
30
20
10
0
14 20 30 40 50 2-Theta - Scale
Figure 4.7: Powder XRD trace of sardignaite with peak positions of the ‘type’ pattern from JCPDS file 01-072-1524 (red).
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4.4.2 Solution studies
Solubility data for the three minerals are reported in Tables 4.1, 4.2, and 4.3. All three phases are comparatively insoluble and dissolve congruently in aqueous HNO3.
+ 3+ 2- Bi2WO6(s) + 4H (aq) ⇋ 2Bi (aq) + WO4 (aq) +2H2O(l) (2)
+ 3+ 2- Bi2MoO6(s) + 4H (aq) ⇋ 2Bi (aq) + MoO4 (aq) +2H2O(l) (3)
3+ 2- + BiMo2O7(OH)∙2H2O(s) + H2O ⇋ Bi (aq) + 2MoO4 (aq) + 3H2O + H (aq) (4)
The pH at equilibrium (1.082, russellite; 1.071 koechlinite; 1.090, sardignaite) was used in the determination of ion speciation patterns using the program COMICS
(Perrin and Sayce, 1967). Individual ion activity coefficients were calculated using the
Davis extension of the Debye-Hückel equation for 298.15 K, lg = –
0.5085z2((I/(1+I)-0.3I), for russellite I = 0.090 mol.dm–3, 3 = 0.042 and 2 = 0.245, for koechlinite I = 0.092 mol.dm–3, 3 = 0.041 and 2 = 0.242, and for sardignaite I =
0.090 mol.dm–3, 3 = 0.043 and 2 = 0.2460, In all instances, o is taken to be unity.
+ + The activity of H (aq), a(H ), in HNO3; 0.0981 M was then calculated and
3+ 2- 2- corresponding activities a(Bi ), a(WO4 ) and a (MoO4 ), were calculated from the solubility data (Tables 4.1, 4.2, and 4.3).
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Table 4.1 Dissolved metal concentrations for russellite
Solution [Bi] ppm [Bi] mol dm-3 -5 1 5.6 2.7 x 10 -5 2 5.6 2.7 x 10 -5 3 5.2 2.5 x 10 -5 4 5.9 2.8 x 10 -5 5 5.8 2.8 x 10 -5 6 5.1 2.4 x 10 -5 Mean 5.5 2.6 x 10 -6 Error 0.30 1.4 x 10
Table 4.2. Dissolved metal concentrations for koechlinite
Solution [Bi] ppm [Bi] mol dm-3 [Mo] ppm [Mo] mol dm-3 5 -5 1 10 4.8 x 10- 1.5 1.6 x 10 -5 -5 2 10 4.8 x 10 1.5 1.6 x 10 -5 -5 3 13 6.2 x 10 1.6 1.7 x 10 -5 -5 4 10 4.8 x 10 1.6 1.7 x 10 -5 -5 5 15 7.2 x 10 1.7 1.8 x 10 -5 -5 Mean 12 5.7 x 10 1.6 1.7 x 10 -5 -7 Error 2.0 9.6 x 10 0.1 5.2 x 10
Table 4.3. Dissolved metal concentrations for sardignaite
Solution [Bi] ppm [Bi] mol dm-3 [Mo] ppm [Mo] mol dm-3 1 0.59 2.8 x 10-6 1.8 2.4 x 10-5 2 0.52 2.5 x 10-6 2.1 2.8 x 10-5 3 0.58 2.8 x 10-6 1.9 2.5 x 10-5 4 0.61 2.9 x 10-6 1.7 2.3 x 10-5 Mean 0.58 2.75 x 10-6 1.9 2.5 x 10-5 Error 0.16 7.4 x 10-7 0.2 3.0 x 10-6
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The pH at equilibrium for russellite was used in the determination of individual ion speciation using COMICS (Perrin and Sayce, 1967). Reliable lg K values for the equations (6), (8), (10), (12), (14), (16), and (18) at I = 0 mol dm–3 were reported by van
Der Lee and Lomenech (2004) and Baes and Mesmer (1976). Correction to I = 0.090, mol dm–3 yields lg K(298.15 K) = –2.63, –5.74, –10.97, –11.42, and –7.12, using the relationships shown by equations (7), (9), (11), (13), and (15). This gave the
2+ + o - - concentration of Bi(OH) (aq), Bi(OH)2 (aq), Bi(OH)3 (aq), HWO4 (aq), and H2WO4
(aq) as 3.7 x 10-8, 3.5 x 10-10 2.6 x 10-14, 2.00 x 10-19, and 3.30 x 10-16 mol.dm–3 respectively.
3+ 2+ + Bi (aq) + H2O(l) ⇋ Bi(OH) (aq) + H (aq) (6)
[Bi(OH)2+].[H+]/[Bi3+] = 10–1.11 (7)
3+ + + Bi (aq) + 2H2O(l) ⇋ Bi(OH)2 (aq) + 2H (aq) (8)
+ + 3+ –3.30 [Bi(OH)2 ].2[H ]/[Bi ] = 10 (9)
3+ 0 + Bi (aq) + 3H2O(l) ⇋ Bi(OH)3 (aq) + 3H (aq) (10)
0 + 3+ –8.21 [Bi(OH)3 ].3[H ]/[Bi ] = 10 (11)
2- + - WO4 (aq) + H (aq) ⇋ HWO4 (aq) (12)
- 2- + +3.5 [HWO4 ]/[ WO4 ][H ] = 10 (13)
2- + - WO4 (aq) + 2H (aq) ⇋ H2WO4 (aq) (14)
-- 2-- + +8.1 [H2 HWO4 ]/[ WO4 ]2[H ] = 10 (15)
2- + - MoO4 (aq) + H (aq) ⇋ HMoO4 (aq) (16)
- 2- + +3.89 [H MoO4 ]/[ MoO4 ][H ] = 10 (17)
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2- + - MoO4 (aq) + 2H (aq) ⇋ H2MoO4 (aq) (18)
- 2- + +7.50 [H MoO4 ]/[ MoO4 ][H ] = 10 (19)
Correction to I = 0.092, mol dm–3 for koechlinite by the method of Baes and
Mesmer (1976), yields lg K(298.15 K) = –1.63, –4.13, –9.14, –9.3 and –7.56, using the relationships shown by equations (7), (9), (11), (13), and (15). This gave the
2+ + o - - concentration of Bi(OH) (aq), Bi(OH)2 (aq), Bi(OH)3 (aq), HWO4 (aq), and H2MoO4
(aq) as 5.10 x 10-7, 1.9 x 10-8, 2.2 x 10--12, 6.10 x 10-17, and 2.90 x 10-16 mol.dm–3 respectively.
Correction to I = 0.090, mol dm–3 for sardignaite by the method of Baes and
Mesmer (1976), yields lg K(298.15 K) = –1.87, –4.52, –9.58, –9.45 and –7.76, using the relationships shown by equations (7), (9), (11), (13), and (15). This gave the
2+ + o - - concentration of Bi(OH) (aq), Bi(OH)2 (aq), Bi(OH)3 (aq), HWO4 (aq), and H2MoO4
(aq) as 3.00 x 10-7, 8.10 x 10-9, 8.7 x 10--13, 7.50 x 10-17, and 3.00 x 10-16 mol.dm–3 respectively.
The above then yield values of lg K for russellite, –16.99±1.5, koechlinite –
24.83±1.5 and sardignaite–20.59±1.50, equations (2), (3) and (4) respectively and the
ө following ΔGf values can be calculated:
ө ө –1 ΔGr (298.15 K) = +55.08. Thus, ΔGf (Bi2WO6, 298.15 K) = –1318.93 ±1.5 kJ mol
ө ө –1 ΔGr (298.15 K) = +7.26. Thus, ΔGf (Bi2MoO6,), 298.15 K) = –1270.78±1.5 kJ mol
ө ө ΔGr (298.15 K) = +45.27. Thus, ΔGf B2MoO7(OH)·2H2O, 298.15 K) = –2176.94 ±1.56 kJ mol–1
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The estimated error takes into account the analytical error of the solubility experiments and errors quoted for the thermochemical data used.
Table 4.4 Thermodynamic quantities used in the calculations (T = 298.15 K).
ө -1 ΔGf /kJ.mol Reference bismoclite –322.1 Kaye and Laby (1995) bismutitea –916.2 ±7.5 see text russellite –1318.93 ±1.5 this study koechlinite –1270.78 ±1.5 this study sardignaite –2176.94 ±1.56 this study o b H2WO4 (aq) –964.51 see text - b HWO4 (aq) –951.95 see text 2- b WO4 (aq) –931.4 see text o b H2MoO4 (aq) –877.64 see text - b HMoO4 (aq) –867.10 see text 2- b MoO4 (aq) –838.50 see text o c Bi(OH)3 (aq) –572.61 see text + c Bi(OH)2 (aq) –363.54 see text Bi(OH)2+(aq)C –138.94 see text Bi3+(aq)c +91.82 see text
CO2(g) –394 Robie and Hemingway (1995) Cl-(aq) –131.2±0.1 Robie and Hemingway (1995)
H2O(l) –237.1±0.1 Cox et al. (1989) a Values have been recalculated using values for H2O(l), CO2(g) and Bi2O3(s) at 298.2 K taken from Robie and Hemingway (1995).bCalculated from Baes and Mesmer (1976) and Martell and Smith (1982). cCalculated using standard electrode potentials from ө 3+ Lovrecek et al. (1985) to determine ΔGf (Bi ) and dissociation constants from van Der Lee and Lomenech (2004).
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4.5 REFERENCES
Ambrino, P., (2013) Sardignaite: BiMo2O7(OH)·2H2O Punta de Su Seinargiu, Sarroch,
Cagliari Province, Sardinia, Italy, photograph, viewed 10 January 2014, <
http://www.mindat.org/photo-566105.html>.
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.
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.
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Anthony, J.W., Bideaux, R.A., Bladh, K.W. and Nichols, M.C. (2003) Handbook of
Mineralogy Volume 5: Borates, Carbonates, Sulfates. Mineral Data Publishing,
Tucson, Arizona.
Baes, C.F. Jr and Mesmer, R.E. (1976) The Hydrolysis of Cations. Plenum Press, New
York.
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.
Birch, W.D., Pring, A., McBriar, E.M. Gatehouse, B.M. and McCammon, C.A. (1998)
3+ Bamfordite, Fe Mo2O6(OH)3·H2O, a new hydrated iron molybdenum
oxyhydroxide from Queensland, Australia: description and crystal chemistry.
American Mineralogist, 83, 172-177.
Clissold, M.E. (2007) Aspects of the supergene geochemistry of copper nickel and
bismuth. PhD thesis unpublished, University of Western Sydney.
Cox, J.D., Wagman, D.D. and Medvedev, V.A. (1989) CODATA Key Values for Thermodynamics. Hemisphere Press, New York.
England, B.M. (1985) Famous mineral localities: the Kingsgate mines. The
Mineralogical Record, 16, 265-289.
Fuchs, P., (2012) Koechlinite: Bi2MoO6 Quartz vein outcrops, Knöttel area (Knötel;
Knödel; Knödlberg), Krupka (Graupen), Krušné Hory Mts (Erzgebirge), Ústí
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Region, Bohemia (Böhmen; Boehmen), Czech Republic, photograph, viewed 10
January 2013, < http://www.mindat.org/photo-477077.htmll>.
Gaines, R.V., Skinner, H.C.W., Foord, E.E., Mason, B. and Rosenzweig, A. (1997)
Dana’s New Mineralogy. Eight edition, John Wiley and Sons, New York.
6+ 5+ Haupt, J., (2011) Gelosaite: BiMo (2-5x)Mo 6xO7(OH)·H2O (0 ≤ x ≤ 0.4) Old 25 Pipe,
Kingsgate, Gough Co., New South Wales, Australia, photograph, viewed 10
January 2013, < http://www.mindat.org/photo-383852.html>.
Hey, M.H. and Bannister, F.A. (1938) Russellite, a new British mineral, with a note on
the occurrence and the accompanying minerals by Arthur Russell. Mineralogical
Magazine, 25, 41-56.
Knight, K.S. (1992) The crystal structure of russellite; a re-determination using neutron
powder diffraction of synthetic Bi2WO6. Mineralogical Magazine, 56, 399-409.
Lang, J.R. and Baker, T. 2001: Intrusion-related gold systems: the present level of
understanding. Mineralium Deposita, 36, 477-489.
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.
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Martell , A. E. And Smith, R. M. (1982) Critical Stability Constants Volume 5: First
Supplement. Plenum Press, New York.
Orlandi, P., Demartin, F., Pasero, M., Leverett, P., Williams, P.A. and Hibbs, D.E.
6+ 5+ (2011) Gelosaite, BiMo (2-5x)Mo 6xO7(OH)·H2O (0 ≤ x ≤ 0.4), a new mineral from
Su Senargiu (Ca), Sardinia, Italy, and a second occurrence from Kingsgate, New
England, Australia. American Mineralogist, 96, 268-273.
Pavel, M.., (2008) Russellite: Bi2WO6 Kara-Oba W deposit, Betpakdala Desert,
Karagandy Province, Kazakhstan, photograph, viewed 10 January 2013, <
http://www.mindat.org/photo-148658.html>.
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.
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.
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., Sharpe, J.L. and Williams, P.A. (2013) Unpublished survey of secondary Bi,
Mo and W minerals in Australian deposits.
87 | P a g e
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.
Sharpe, J.L. and Williams (2004) Secondary bismuth and molybdenum minerals from
Kingsgate, New England district of New South Wales. Australian Journal of
Mineralogy, 10, 7-12
Sarafian, P.G. and Furbish, W.J. (1965) Solubilities of natural and synthetic
ferrimolybdite. American Mineralogist, 50, 223-226.
Schaller, W.T. (1916) Koechlinite (bismuth molybdate), a new mineral. United States
Geological Survey Bulletin, 610, 10-34.
Teller, R.G., Brazdil, J.F., Grasselli, R.K. and Jorgensen, J.D. (1984) The structure of
bismuth molybdate, Bi2MoO6, by powder neutron diffraction. Acta
Crystallographica, C40, 2001-2005.
van den Elzen, A.F. and Rieck, G.D. (1973) Redetermination of the structure of
Bi2MoO6, koechlinite. Acta Crystallographica, B29, 2436-2438.
van der Lee, J. and Lomenech, C. (2004) Towards a common thermodynamic database for speciation models. Radiochimica Acta, 92, 811-818.
Wittern, A. (2001) Mineralfundorte in Deutschland. Schweizerbart, Stuttgart.
88 | P a g e
Zemann, J. (1956) Die Kristallstruktur von Koechlinit, Bi2MoO6. Contributions to
Mineralogy and Petrology, 5, 139-145.
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CHAPTER 5
SMIRNITE AND CHEKHOVICHITE
90 | P a g e
5.1 ABSTRACT
The Secondary Bi-Te minerals chekhovichite, Bi2Te4O11, and smirnite, Bi2TeO5, were investigated to determine their role as path finder minerals in exploration geochemistry due to the association of Bi-Te with precious metal deposits (McPhail,
1995). Syntheses and stability studies of the two minerals have been undertaken.
Solubilities in aqueous HNO3 were determined at 298.2 K and the data obtained used to
ө ө calculate values of ΔGf at the same temperature. The derived ΔGf (298.2 K) values for chekhovichite, (–1457.23 ± 0.5 kJ mol–1), and smirnite (–820.92 ± 1.0 kJ mol–1) have been used in subsequent calculations to determine their relative stabilities to each other and their dispersion in the supergene zone.
5.2 INTRODUCTION
The occurrence of native Te is observed in some deposits, but Te most commonly occurs in precious metal and sulfosalt minerals (Afifi et al., 1988; Jaireth,
1991). Of the known secondary species containing essential Bi and Te (Chapter 2, Table
1), the only phases that have any reasonable distribution include chekhovichite,
Bi2Te4O11, smirnite Bi2TeO5, and to a lesser extent pingguite Bi6Te2O13. These three minerals form by oxidation of Bi-Te sulfosalts, which are common accessories in a number of deposits. Chekhovichite was originally reported by Spiridonov et al. (1987) where it was found at the Zod Mine (Sotk deposit), Vardenis, Gelark’unik’, Armenia, the Northern Aksu deposit, Stepnogorsk, Akmolinskaya Oblast’, Kazakhstan and
Zhana-Tyube Au deposit, Akmolinskaya Oblast’, Kazakhstan. Spiridonov et al., (1987) reported that chekhovicihite was associated with a number of Bi and Te sulfosalts and known secondary phases, tetradymite, tellurobismuthite, plumbotellurite, PbTeO3,
91 | P a g e
Figure 5.1: Chekhovichite from the Zod Mine (Sotk deposit), Vardenis, Gelark'unik' Province (Geghark'unik'), Specimen size 3.5 x 3.5 x 3 mm (Bosi, 2012)
“emmonsite” and tripuhyite. Rossell et al. (1992) have reported a structure for chekhovichite, and a synthesis was reported by Szaller et al. (1996). The crystal structure of smirnite, Bi2TeO5, was reported in Mercurio et al. (1983) and was found from the same type locality as chekhovichite (Spiridonov et al., 1987). Smirnite is associated with tellurobismuthite, tetradymite and volynskite and also has a known synthesis (Ok, 2001).
92 | P a g e
Figure 5.2: Greyish to olive-green crusts of smirnite over quartz and metallic-grey tsumoite from the Shilovo-Isetskii mine, Ekaterinburg, Sverdlovskaya Oblast', Middle Urals, Urals Region, Russia. FOV is ~12x10 mm (Pavel, 2007).
There are other known bismuth tellurite minerals. The mineral “montanite”,
Bi2TeO6·2H2O or Bi2(OH)4TeO4, is listed by the IMA as doubtful despite 19 occurrences to date as its structure is yet to be confirmed (Palache et al., 1951;
Kazachenko et al., 1980). Another species which contains essential molybdenum is the mineral chiluite, Bi6Te2Mo2O21, discovered from the Chilu deposit, Fu’an County,
Ningde Prefecture, China (Yang et al., 1989; Deng and Yang, 1993). The mineral is rare and occurs as a replacement of joséite inclusions in bismuthinite and as coatings on
93 | P a g e koechlinite, with molybdenite reported to be present in the primary assemblage. Despite a known type locality, the mineral’s structure is uncertain. The synthetic analogue was prepared, but the mineral requires further study as the cell constants are not well- defined. The mineral was originally supposed to be hexagonal (Yang et al., 1989), but subsequent work on the synthetic analogue shows it to be orthorhombic (Deng and
Yang, 1993).
5.3 EXPERIMENTAL
5.3.1 Syntheses of smirnite and chekhovichite
The synthesis of chekhovichite, Bi2Te4O11, was adapted from the synthesis reported by Szaller et al. (1996). Bi2O3 and TeO3 were both initially annealed in air
o (450 C) and then ground and sieved (-63 μm), the smaller fraction was used. A Bi2O3:
o 4TeO3 mixture was sealed in a quartz tube and heated at 720 C for 2 hours. The charge was cooled slowly (50oC/hour) to ambient temperature then heated again (500oC) for two days.
The synthesis of smirnite, Bi2TeO5, was adapted from the method reported by
Ok et al. (2001). A stoichiometric mixture of Bi2O3 (1.72 mmol) and TeO2 (1.72 mmol) was thoroughly ground and sealed in a quartz tube and placed in a furnace (690oC) for
36 hours. The mixture was cooled to ambient temperature and the product collected as above.
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5.3.2 Solubility Studies
Solubility studies of the Te minerals were undertaken using sealed 250 cm3 conical QuickfitR flasks maintained at 25.0 0.2oC in a thermostatted water bath inside a controlled temperature room at the same temperature. Measurements of pH were made using a Radiometer ION450 apparatus fitted with a combination electrode. The minerals
(ca 0.1 g) were added to a series of conical flasks containing 100 cm3 of standardised
HNO3; 0.1065 M. The flasks were left for a period of time until the pH of a paired flask, which was monitored periodically, reached stability. Resulting solutions were filtered through a WhatmanR GF/F fibreglass filter and collected in clean PET bottles.
Dissolved metal concentrations were determined using ICP-MS by a NATA-compliant commercial laboratory (mgt | LabMark Environmental Testing Australia Pty Ltd).
5.4 RESULTS
5.4.1 Syntheses of smirnite and chekhovichite
High purity, single phase samples of chekhovichite and smirnite were obtained by the solid state methods mentioned above and were characterised by powder X-ray diffraction. Unit cell parameters were refined in LAPOD (Langford, 1973) and obtained values for chekhovichite of a = 18.897(3), b = 7.952(2), and c = 6.991(1) Å, and for smirrnite of a = 16.442(8), b = 5.511(2) and c = 11.576(5) Å, these unit cell dimensions agree well with those reported by Rossell et al. (1992) and Mercurio et al. (1983).
95 | P a g e
600
500
400
300
Lin (Counts) Lin
200
100
0
5 10 20 30 40 50 60 70 2-Theta - Scale Figure 5.3: Powder XRD trace of checkhovichite with peak positions of the ‘type’ pattern from JCPDS file 01-081-1330 (red).
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1000
900
800
700
600
500
Lin (Counts) Lin
400
300
200
100
0
5 10 20 30 40 50 60 70 2-Theta - Scale Figure 5.4: Powder XRD trace of smirnite with peak positions of the ‘type’ pattern from JCPDS file 00-038-04200 (red).
97 | P a g e
5.4.2 Solubility Studies
The dissolution of chekhovichite, and smirnite are described in equations (1) and (2) respectively.
+ 3+ + Bi2Te4O11(s) + H2O(l) + 10H ⇋ 2Bi + 4H3TeO3 (1)
+ 3+ + Bi2TeO5(s) + 7H ⇋ 2Bi + H3TeO3 2H2O(l) (2)
Individual ion activity coefficients were calculated using the Davis extension of the Debye-Hückel equation for 298.15 K, lg = –0.5085z2(I/(1+I) – 0.3I). For chekhovichite, I = 0.1069 mol dm–3, 3 = 0.1045 2 = 0.3665 and = 0.778. For smirnite I = 0.1068 mol dm–3, 3 = 0.1046, 2 = 0.3666 and = 0.7781. In all
o + + instances, is taken to be unity. The activity of H (aq), a(H ), in HNO3; 0.1065 M was
3+ + then calculated and corresponding activities a(Bi ) and a(H3TeO3 ) calculated from the solubility data in Tables 5.1 and 5.2 .
The pH at equilibrium (1.087; chekhovichite) was used in the determination of individual ion speciation using COMICS (Perrin and Sayce, 1967). A reliable lg K value for equation (3) of lg K(298.15 K) = –2.83 and for equation (5) of lg K(298.15 K) = –
9.21 at I = 0 mol dm–3 was reported by McPhail (1995). Correction to I = 0.1069, mol dm–3 by the method of Baes and Mesmer (1976), yields lg K(298.15 K) = –2.94 and –
9.21 respectively. Using the relation shown in equation (4), the concentration of
o -8 - –16 –3 H2TeO3 (aq) is 1.663 x 10 and HTeO3 (aq) = 7.31 x 10 mol.dm .
98 | P a g e
Table 5.1. Dissolved metal concentrations for chekhovichite Solution [Bi] ppm [Bi] mol dm-3 1 18 8.613 x 10-5 2 19 9.092 x 10-5 3 18 8.613 x 10-5 4 19 9.092 x 10-5 5 19 9.092 x 10-5 6 18 8.613 x 10-5 Mean 18.5 8.853 x 10-5 Error ±0.5 ±2.393 x 10-5
Table 5.2. Dissolved metal concentrations for smirnite Solution [Bi] ppm [Bi] mol dm-3 1 12 5.742 x 10-5 2 12 5.742 x 10-5 3 11 5.264 x 10-5 4 12 5.742 x 10-5 5 12 5.742 x 10-5 6 13 6.221 x 10-5 Mean 12 5.742 x 10-5 Error ±1.0 ±4.79 x 10-6
+ o + H3TeO3 (aq) ⇋ H2TeO3 (aq) + H (aq) (3)
o + + [H2TeO3 ] [H ]/[H3TeO3 ] (4)
+ - + H3TeO3 (aq) ⇋ HTeO3 (aq) + H (aq) (5)
- + + [HTeO3 ] 2.[H ]/[H3TeO3 ] (6)
99 | P a g e
3+ 2+ + Bi (aq) + H2O(l) ⇋ Bi(OH) (aq) + H (aq) (7)
[Bi(OH)2+].[H+]/[Bi3+] (8)
3+ + + Bi (aq) + 2H2O(l) ⇋ Bi(OH)2 (aq) + 2H (aq) (9)
+ + 3+ [Bi(OH)2 ].2[H ]/[Bi ] (10)
3+ 0 + Bi (aq) + 3H2O(l) ⇋ Bi(OH)3 (aq) + 3H (aq) (11)
0 + 3+ [Bi(OH)3 ].3[H ]/[Bi ] (12)
Reliable lg K values for equation (7), (9) and (11) of lg K(298.15 K) = –1.11, –
3.30 and –8.21 at I = 0 mol dm–3 were reported by van Der Lee and Lomenech (2004).
Correction to I = 0.1069, mol dm–3 by the method of Baes and Mesmer (1976), yields lg
K(298.15 K) = –1.65, –4.17 and –9.19. Using the relationships shown by equations (8),
2+ + o (10) and (12), the concentration of Bi(OH) (aq), Bi(OH)2 (aq) and Bi(OH)3 (aq) are
1.886 x 10-5, 6.958 x 10-7 and 8.12 x 10-11 mol dm–3, respectively.
The pH at equilibrium (1.109; smirnite) was used in the determination of individual ion speciation using COMICS (Perrin and Sayce, 1967). Correction to I =
0.1068, mol dm–3 by the method of Baes and Mesmer (1976), yields lg K(298.15 K) = –
2.94 for equation (3) and lg K(298.15 K) = –9.21 for equation (4). Using the relation
o -8 - shown in equation (4), the concentration of H2TeO3 (aq) is 1.047 x 10 and HTeO3 (aq)
= 4.466 x 10–16 mol dm–3. Correction to I = 0.1068, mol dm–3 by the method of Baes and
Mesmer (1976) for equations (8), (10) and (12), yields lg K(298.15 K) = –1.66, –4.17 and –9.19. Using the relationships shown by equations (8), (10) and (12), the
100 | P a g e
2+ + o -5 concentration of Bi(OH) (aq), Bi(OH)2 (aq) and Bi(OH)3 (aq) are 1.23 x 10 , 4.784 x
10-7 and 5.752 x 10-11 mol.dm–3 respectively.
Table 5.3. Thermodynamic quantities used in the calculations (T = 298.15 K).
ө -1 ΔGf /kJ.mol Reference chekhovichite Bi2Te4O11(s) –1457.23 ± 0.5 this study smirnite Bi2TeO5(s) –820.92 ± 1.0 this study
o Bi(OH)3 (aq) –572.61 ± 0.1 van Der Lee and Lomenech (2004)
+ Bi(OH)2 (aq) –363.54 ± 0.1 van Der Lee and Lomenech (2004)
Bi(OH)2+(aq) –138.94 ± 0.1 van Der Lee and Lomenech (2004) + H3TeO3 (aq) -490.7 McPhail (1995)
0 H2TeO3 (aq) -474.6 McPhail (1995)
- HTeO3 (aq) -438.2 McPhail (1995)
2- TeO3 (aq) -384 McPhail (1995)
Cl-(aq) –131.2 ± 0.1 Robie and Hemingway (1995)
H2O(l) –237.1 ± 0.1 Cox et al. (1989)
+ + The activity of H (aq), a(H ), in 0.1084 and 0.0104 M HNO3 was then
3+ + o - calculated and corresponding activities a(Bi ), a(H3TeO3 ), a(H2TeO3 ), a(HTeO3 ),
2+ + o a(Bi(OH) ), a(Bi(OH)2 ), and a(Bi(OH)3 ), were calculated from the solubility data.
This yields values of lg K for equations (1) and (2) of –14.86 ± 0.10 and -6.95 ± 0.12 respectively. Use of the appropriate data in Table 5.3 yields corresponding values for
ө –1 ө ΔGr (298.15 K) = +84.83 and +39.66 kJ mol . Thus, ΔGf (Bi2Te4O11, s, 298.15 K) = –
–1 ө –1 1457.23 ± 0.5 kJ mol and ΔGf (Bi2TeO5, s, 298.15 K) = –820.92 ± 1.0 kJ mol . The
101 | P a g e estimated error takes into account the analytical error of the solubility experiments and errors quoted for the thermochemical data used.
5.5 REFERENCES
Afifi, A., Kelly, M., and Essene, E.J. (1988) Phase relationships among tellurides,
sulphides and oxides: I. Thermochemical data and calculated equilibria. Economic
Geology, 83, 337-394.
Baes, C.F. Jr and Mesmer, R.E. (1976) The Hydrolysis of Cations. Plenum Press, New
York.
4+ Bosi, R. (2012) Chekhovichite: Bi2Te 4O11 Zod Mine (Sotk deposit), Vardenis,
Gelark'unik' Province (Geghark'unik'), Armenia, photograph, viewed 6 March
2014, < http://www.mindat.org/photo-492561.html l>
Cox, J.D., Wagman, D.D. and Medvedev, V.A. (1989) CODATA Key Values for
Thermodynamics. Hemisphere Press, New York.
Deng, M. and Yang, X. (1993) Bi6Te2Mo2O21 - a new synthetic crystal and its physical
properties. Journal of Crystal Growth, 128, 876-879.
Jaireth, S. (1991) Hydrothermal geochemistry of Te, Ag2Te, and AuTe2 in epithermal
precious metal deposits. Economic Geology, 37. James Cook University of North
Queensland, Australia.
102 | P a g e
Kazachenko, V.T., Fat’yanov, I.I. and Chubanov. (1980) Discovery of a lead-containing
variety of montanite. Doklady Academii Nauk SSSR., 225 , 968-971
Langford, J.I. (1973) Least-squares refinement of cell dimensions from powder data by
Cohen's method. Journal of Applied Crystallography, 6, 190-196.
McPhail, D.C. (1995) Thermodynamic properties of aqueous tellurium species between
25 and 350°C. Geochimica et Cosmochimica Acta, 59, 5, 851-866.
Mercurio, D., El Farissi, M., Frit, B. and Goursat, P. (1983) Etude structurale et
densification d'un nouveau materiaux piezoelectrique: Bi2TeO5. Materials
Chemistry and Physics, 9, 467-476.
Ok, K.M., Bhucanesh, N.S.P. and Halasyamani, P.S. (2001) Bi2TeO5: synthesis,
structure and powder second harmonic generation properties, Inorganic Chemistry,
40, 1978-1980.
Palache, C., Berman, H. and Frondel, C. (1951) Dana’s System of Mineralogy, 2, 636-
637
4+ Pavel, M. (2007) Smirnite : Bi2Te O5, Tsumoite : BiTe Shilovo-Isetskii mine,
Ekaterinburg, Sverdlovskaya Oblast', Middle Urals, Urals Region, Russia,
photograph, viewed 6 March 2014,
103 | P a g e
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.
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.
Rossell, H.J., Leblanc, M., F´erey, G., Bevan, D.J.M., Simpson, D.J. and Taylor, M.R.
(1992) On the crystal structure of Bi2Te4O11. Australian Journal of Chemistry, 45,
1415-1425.
Spiridonov, E.M., Petrova, I.V., Demina, L.A., Dolgikh, V.I. and Antonyan, G.M.
(1987) The new mineral chekhovichite (Bi2Te4O11). Moscow University Geology
Bulletin, 42, 71-75.
Szaller, Z., Pöppl, L., Lovas, G., and Dódony, I. (1996) Study of the formation of
Bi2Te4O11, Journal of Solid State Chemistry, 121, 251-261.
van der Lee, J. and Lomenech, C. (2004) Towards a common thermodynamic database
for speciation models. Radiochimica Acta, 92, 811-818.
Yang, X., Li, D., Wang, G., Deng, M., Chen, N. and Wang, S. (1989) A study of
chiluite - a new mineral found in Chilu, Fujian, China. Acta Mineralogica Sinica, 9,
9-14; American Mineralogist, 76, 666 (1990).
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CHAPTER 6
Conclusions
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6.1 ABSTRACT
A model of the dispersion of bismuth in the supergene zone has been developed in this work. This was done by using the free energy of formation values and equations derived in this thesis for cannonite, rooseveltite, koechlinite, russellite and smirnite were compared to the two most common bismuth minerals bismoclite and bismutite. To make this determination and provide a clear and reasonable understanding of the dispersion of bismuth, an assessment of the Cobar region and Kingsgate region of NSW was undertaken. This was done by reviewing the respective environments, the known mineralogy and the reported geochemical data, as well as drawing upon previous chapter’s data and conclusions to develop a reverse water solubility model, which has major implications on the understanding of bismuth in the supergene zone.
6.2 INTRODUCTION
Every mineral deposit has, in some respects, a unique surface geochemical
“signature” due to differences in geological, geomorphological and environmental settings. On the contrary many similarities in regards to elemental dispersion characteristics may be displayed over extensive regions, either generically, for many commodities, or more specifically for one commodity. A prerequisite for mineral exploration in the supergene environment is the understanding and knowledge of the geochemical “signature” of particular mineralisation (Leverett et al., 2004). The dispersion of elements in the environment is heterogeneous and particular elements may be widely dispersed compared to others, therefore it is necessary to have some understanding of the chemical as well as physical controls that govern this dispersion.
Therefore, in the case of this study to draw conclusions on a proper understanding of the
106 | P a g e dispersion of Bi in the environment will depend on appreciation of its low-temperature aqueous chemistry and knowledge of the secondary Bi minerals that serve to buffer the element between the solid and solution states.
Weathering, in a geochemical exploration context, causes the destruction of primary ore deposits and the dispersion of ore and pathfinder elements in the surrounding regolith. Conversely, it may also result in the supergene enrichment of some deposits and promote the formation of secondary orebodies. To understand the history and potential mechanisms and pathways of migration of ore and pathfinder elements in regolith, it is necessary to unravel the complex superposition of events that may have occurred during regolith-landscape evolution. According to McKinnon et al.
(2005) the ability of minerals to resist chemical weathering (i.e., dissolution) is paramount when considering the hydromorphic dispersion of elements from an orebody and, inter alia, the formation of geochemical anomalies. If appropriate geochemical parameters can be estimated, and with an assumption that the mineral phases of interest are in thermodynamic equilibrium with the groundwater, it is possible to evaluate the volume of groundwater needed to completely dissolve a known quantity of a mineral.
This approach can be used to calculate the volume of proxy groundwater solution required to dissolve one kilogram of bismutite (for example) at various pH values. This is achieved by dividing the number of moles of bismuth in one kilogram of bismutite by the total dissolved concentration of bismuth at any particular pH. The same calculation can be used for other mineral species and the calculated volumes are estimated, as factors such as changes in groundwater compositions during dissolution, the time required for each system to reach equilibrium, and even variations in temperature will serve to alter them. Even with these factors considered, the magnitude of differences in
107 | P a g e results implies that some species are relatively resistant to chemical weathering, while others will dissolve in quite small quantities of groundwater.
6.3 Discussion of Data
6.3.1 Chapter 2 Discussion
The work completed in chapter two can be used to determine the relationships which control bismuth dispersion. The two basic carbonates bismutite, Bi2O2CO3, and a synthetic phase of composition Bi4O4CO3(OH)2 must be taken into account. Taylor et al. (1984) determined thermochemical data for both of these phases, relative to that of
ө bismite, α-Bi2O3. ΔGf values have been recalculated using values for H2O(l), CO2(g) and Bi2O3(s) at 298.2 K taken from Robie and Hemingway (1995) in order to establish consistency and to eliminate error between data sets. This yields values of
ө ө ΔGf (Bi2O2CO3, bismutite, 298.2 K) and ΔGf (Bi4O4CO3(OH)2, 298.2K) of -916.2 ± 7.5
-1 and -1649.9 ± 9.0 kJ mol , respectively. It is immediately apparent that Bi4O4CO3(OH)2
-3.5 forms only at p(CO2) values below ambient (10 ) and that bismite is thermodynamically unstable with respect to Bi4O4CO3(OH)2 under ambient conditions
-5.5 when H2O is present or with 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, when exposed to air, undergoes surface carbonation and that the preparation of pure Bi2O3 requires heating the samples in an air stream at elevated temperatures (Barreca et al., 2001; Levin and Roth, 1964). 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, bismoclite, BiOCl
ө and cannonite (Figure 6.1). A value for ΔGf (BiOCl, bismoclite, 298.2 K), of -322.1 kJ
108 | P a g e mol-1, was taken from Kaye and Laby (1995). The equilibrium conditions for equation
ө - (1), (3) and (5) was then calculated using the data listed above, with ΔGf (Cl (aq), 298.2
-1 ө 2- K) = -131.2 kJ mol (Robie and Hemingway, 1995), and ΔGf (SO4 (aq),298.2 K) = -
744.0± 0.4 kJ mol-1 (Cox et al., 1989) this gives equation (2), (4) and (6) which are used in Figure 6.1.
+ - Bi2O2CO3(s) + 2H (aq) + 2Cl (aq) ⇋ 2BiOCl(s) + CO2(g) + H2O(l) (1)
- pH = 8.50 – ½lg p(CO2) + lg a(Cl ) (2)
- 2- Bi2(SO4)O(OH)2(s) + 2Cl (aq) ⇋ 2BiOCl(s) + SO4 (aq) + H2O(l) (3)
- 2- lg a(Cl ) = {-8.219 + lg a(SO4 )}/2 (4)
2- + Bi2O2CO3(s) + SO4 (aq) + 2H (aq) ⇋ Bi2(SO4)O(OH)2(s) + 2CO2 (g) (5)
2- pH = {8.727 –lg a(pCO2) + lg a(SO4 )}/2 (6)
pH
0 1 2 3 4 5 6 7 8 9 10 11 0
-1
-2
- -3 Bismoclite -4
-5 Bismutite
log activit ofCl activitlog -6
-7 Cannonite
-8
109 | P a g e
2- Figure 6.1: Relationship of cannonite, with common bismutite and bismoclite. a(SO4 )
-2 -3.5 -2.5 = 10 . Dashed and solid lines represent p(CO2) = 10 and p(CO2) = 10 (solid line),
respectively.
2- It is apparent that bismoclite dominates the stability field even at high a(SO4 ), thus for cannonite to persist in natural settings requires the depletion of the [Cl-] and low pH. The formation of bismutite also requires almost complete exhaustion of both
Cl-(aq) as shown by Figure 6.1. It is clear that cannonite has a contribution to the immobilisation of Bi, but not as great as that of bismoclite. Thus, the possibility for the significantly smaller number of occurrences of cannonite as compared to bismoclite reflects the persistent acidic conditions at localities where the a(Cl-) is slow enough or expelled, without hosting bismoclite. Furthermore, the occurrence of riomarinaite is limited to the minerals’ contact time with ground waters due to it being metastable.
6.3.2 Chapter 3 Discussion
The following equations describe the relationships which are considered to control the stability of rooseveltite, preisingerite and atelestite. The equilibrium conditions for equation (7, 9 and 11) were calculated using the data listed in Table 3.4, which gives equations (8), (10) and (11).
0 3Bi2(AsO4)O(OH)(s) +H3AsO4 (aq) ⇋ 2Bi3(AsO4)2O(OH)(s) + 2H2O(l) (7)
ө ΔGr = –46.29. Thus, Log K = 8.108
0 Log K = 1/ a(H3AsO4 ) (8)
0 2BiAsO4(s) + 2H2O(l) ⇋ Bi2(AsO4)O(OH)(s) + H3AsO4 (aq) (9)
110 | P a g e
ө ΔGr = +38.69 Thus, Log K = –6.777
0 Log K = a(H3AsO4 ) (10)
0 3BiAsO4(s) + 2H2O(l) ⇋ Bi3(AsO4)2O(OH)(s) + H3AsO4 (aq) (11)
ө ΔGr = +34.84. Thus, Log K = –6.111
0 Log K = a(H3AsO4 ). (12)
0 The relative stability of the three phases depends only on the a(H3AsO4 ). Thus rooseveltite is the favourable bismuth arsenate formed in secondary oxidised environments, despite having fewer reported localities than preisingerite and atelestite.
As previously stated, the numerical values reported from mindat.org are only a guide.
Below are the equations for the relationship between rooseveltite and bismoclite, which
ө are shown in equations (13) and (14) where ΔGr = -3.64 and log K = 0.64; therefore bismoclite is favourable in an environment with an appreciable a(Cl-).
- + 0 BiAsO4(s) + Cl (aq) + H (aq) + H2O(l) ⇋ BiOCl(s) + H3AsO4 (aq) (13)
0 - log K = log a(H3AsO4 ) – log a(Cl ) + pH (14)
This work has determined the conditions under which the rare minerals rooseveltite, preisingerite and atelestite can form under ambient conditions in the oxidised zones of Bi-bearing deposits. Therefore solution conditions which contain
0 H3AsO4 must be observed for the formation and stability of the basic Bi-As minerals.
Furthermore in these environments, it is possible that they affect other secondary Bi species in regards to the immobilisation of Bi in the supergene environment. This
111 | P a g e conclusion is significant as it provides a more refined focus on other secondary Bi phases that play important roles in buffering dissolved Bi species in solution.
6.3.3Chapter 4 Discussion
Figure 6.2 and Figure 6.3 describe the relationships which are considered to control the stability of koechlinite and russellite with bismoclite and bismutite. The equilibrium conditions were calculated using the data listed in Table 4.4, with respect to
2- 2- the various speciation of MoO4 and WO4 across the range of pH 0-11. It is apparent from this work that we can conclude that the dominant bismuth secondaries are
2- 2- koechlinite and russellite. Even when the activity of either MoO4 or WO4 is low, in this case 10-6 both koechlinite and russellite dominate the stability field.
pH 0 1 2 3 4 5 6 7 8 9 10 11 0
-1
- -2 bismoclite -3 -4 -5 -6 bismutite
Log activity of Cl of activityLog -7 -8 koechlinite -9 -10
Figure 6.2: Stability relationships of koechlinite with other common Bi minerals. -6 -3.5 -2.5 The activity of total dissolved Mo(VI) = 10 and pCO2 = 10 (dashed line) and 10 (solid line). The breaks in the boundary between koechlinite and bismoclite correspond
112 | P a g e
2- - - to those points where a(MoO4 ) = a(HMoO4 ) at about pH 5 and where a(HMoO4 ) = O a(H2MoO4 ) at about pH 2.
pH 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 0
-1 bismoclite
- -2 -3 -4 bismutite -5 -6 -7 Log activity of Cl of activityLog russellite -8 -9 -10
Figure 6.3: Stability relationships of russellite with other common Bi minerals. The -6 -3.5 -2.5 activity of total dissolved W(VI) = 10 and pCO2 = 10 (dashed line) and 10 (solid line). The break in the boundary between russellite and bismoclite corresponds to the 2- O points where a(WO4 ) = a(H2WO4 ) at about pH 3. No data exist in the literature for 0 the first ionisation constant of H2WO4 (aq).
Equation (15) describes the relationship between koechlinite and sardignaite.
ө Where ΔGr = +63.30, therefore the formation of koechlinite is more favourable to that of sardignaite
0 + 3+ Bi2MoO6(s) + H2MoO4 (aq) +3H (aq) ⇋ BiMo2O7(OH)∙2H2O(s) + Bi (aq) (15)
113 | P a g e
This chapter has established that the common yellow coloured secondary minerals of the Kingsgate region of NSW formerly assumed to be ferrimolybdite, are in fact koechlinte or russellite and as such reported specimens need to be examined by X- ray diffraction or Scanning Electron Microscopy to determine the difference, furthermore the minerals koechlinite and russellite dominate the site (Chapter 1
Appendix A). Also established are the conditions in which russellite, koechlinite and sardignaite can form under ambient conditions in the oxidised zones of Bi-Mo and Bi-
W deposits. Both koechlinite and russellite are stable phases and play a significant effect, in relation to other secondary Bi species, and persist even at low [Mo] and [W], in the immobilisation of Bi in the supergene environment of the Kingsgate Region of
NSW. This conclusion is important as it has refined our understanding of secondary Bi-
Mo and Bi-W phases which control the buffering dissolved Bi species in solution. This is discussed further in this chapter in section 6.6
6.3.4.Chpater 5 Discussion
Equation (16) describes the relationship between smirnite and chekhovichite.
+ + Bi2TeO5 (s) + 3 H3TeO3 (aq) ⇋ Bi2Te4O11 (s) + 3H2O(l) + 3H (aq) (16)
ө Where ΔGr = +124.49, the formation of smirnite is more favourable to that of chekhovichite as shown in Figure 6.4
114 | P a g e
pH 0 2 4 6 8 10 0
-2
+ 3 -4 smirnite
-6
TeO 3 -8 -10 -12 -14
Log activity of H of activityLog -16 chekovichite -18 -20
Figure 6.4: Stability field diagram of smirnite and chekhovichite.
Equation (17) and (18) describes the relationship between smirnite and
+ 0 ө bismoclite for the species H3TeO3 (aq) and H2TeO3 (aq)where ΔGr = –51.58 and –
35.48 respectively.
- + + Bi2TeO5 (s) + 2Cl (aq) + 3H (aq) ⇋ 2BiOCl(s) + H3TeO3 (aq) (17)
- + 0 Bi2TeO5(s) + 2Cl (aq) + 2H (aq) ⇋ 2BiOCl(s) + H2TeO3 (aq) (18)
This study has established the conditions in which smirnite and chekovichite can form under ambient conditions in the oxidised zones of Bi-Te bearing deposits. Smirnite is the more favourable phase and plays a significant effect on the immobilisation and
115 | P a g e dispersion of bismuth in oxidising environments as seen in Figure 6.4 even though Bi-
Te mineralogy is rare. This conclusion has further refined our understanding of secondary Bi-Te phases which control the buffering dissolved Bi species in ground water solutions and can be used with previous work and data to make a fair assessment on the dispersion of bismuth in the oxidised environment.
6.4 Reverse Ground Water Modelling
For the chosen conditions of the model, an equation was derived for every conceivable complex and hydrolysed species of Bi3+ which are listed in Table 6.1
ө whereby state terms have been omitted for simplicity and the ΔGf values used for the minerals modelled are those listed in previous chapters of this thesis. Calculated activities of dissolved species at equilibrium over the pH range from 0 to 11 for each mineral of interest were then calculated and summed to yield a total dissolved [Bi3+] in each case. Model conditions considered were for a(Cl–) = 10-1 (comparatively saline conditions) and 10–4 (simulating rain water-flushed conditions), and p(CO2) = 10–3.5
–2.5 2– -4 (atmospheric) and 10 (simulating soil atmospheric levels) and a(SO4 )= 10 . No correction for ionic activity coefficients were made as this does not affect the conclusions that may be drawn.
116 | P a g e
Table 6.1: Data used in species distributions in solutions at equilibrium with
solid phases. State terms have been omitted for simplicity. Data used in species
distributions in solutions at equilibrium with solid phases.
Equation lg K Ref 3+ 2+ + Bi + H2O ⇋ BiOH + H -1.11 1 3+ + + Bi + 2H2O ⇋ Bi(OH)2 + 2H -3.30 1 3+ 0 + Bi + 3H2O ⇋ Bi(OH)3 + 3H -8.21 1 3+ - + Bi + 4H2O ⇋ Bi(OH)4 + H -21.11 1 3+ 6+ + 6Bi + 12H2O ⇋ Bi6(OH)22 + 12H -0.33 ±0.1 2 6+ 7+ + 1.5Bi6(OH)22 + 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 Bi3+ + Cl- ⇋ BiCl2+ 2.4 2, 3 3+ - + Bi + 2Cl ⇋ BiCl2 3.5 2, 3 3+ - Bi + 3Cl ⇋ BiCl3 5.4 2, 3 3+ - - Bi + 4Cl ⇋ BiCl4 6.1 2, 3 3+ - 2- Bi + 5Cl ⇋ BiCl5 6.7 2, 3 3+ - 3- Bi + 6Cl ⇋ BiCl6 6.6 2, 3 3+ 2- + Bi + SO4 ⇋ BiSO4 2.01 4 3+ 2- - Bi + 2SO4 ⇋ Bi(SO4) 3.41 4 3+ 2- 3- Bi + 3SO4 ⇋ Bi(SO4)3 4.6 4 2- 5- Bi3+ + 4SO4 ⇋ Bi(SO4)4 4.88 4 1: van Der Lee and Lomenech (2004); 2: Lovereček et al., (1985); 3: Smith and Martell (1976); 4: Fedorov et al., (1971)
6.5 BISMUTH MODEL FOR THE COBAR REGION
The Cobar region is a major metallogenic province located within the Lachlan old Belt and has been explored and mined since the late 1800’s. Exploration in this region is difficult due to the complex regolith, deep weathering and extensive transported cover components, as well as by the narrow and deep style and geometry of the deposits. Due to the large ore deposits of the region, the geology is relatively well-
117 | P a g e known and has been reported and updated (Andrews, 1911; Rayner, 1969; McClatchie,
1971; Suppel, 1982; Gilligan and Byrnes, 1994; Stegman and Pocock, 1996; Stegman,
2001; Stegman and Reynolds, 2005). Also, the completion of CRC LEME (2001-2008) covers much of the information on Cobar-style deposits and as such it is not assessed in this body of work.
However in regards to the role of bismuth, a proper assessment is still to be made. Berthelsen (2004) noted that there is notable gold–bismuth and gold–copper correlation in the deposits at Cobar (i.e. New Cobar, Peak, Perseverance and the New
Occidental mines). Minor primary bismuth mineralisation is a feature of Cobar-style mineralisation (Andrews, 1911; Rayner, 1969; McClatchie, 1971; Suppel, 1982;
Gilligan and Byrnes, 1994; Stegman and Pocock, 1996; Reynolds, 1998; Stegman,
2001; Stegman and Reynolds, 2005). Native bismuth and bismuthinite have been discovered along with ikunolite, Bi4(S,Se)4, maldonite, Au2Bi, guanajuatite, Bi2(Se,S)3, volynskite, AgBiTe2, and lilianite, Pb3Bi2(S,Se)6 (Stegman and Pocock, 1996;
Reynolds, 1998; Stegman and Reynolds, 2005). Reported secondary bismuth mineralisation in the Cobar Basin include bismutite (Bi2O2CO3), identified at the New
Cobar deposit (McKinnon, 2003) and the C.S.A. deposit (Stegman and Reynolds,
2005), as well as bismutite, bismite (Bi2O3) and bismoclite (BiOCl) from the Mount
Allen mine (Suppel and Gilligan, 1993).
Taking into consideration the common and rare secondary bismuth minerals and know bismuth sulfosalts mentioned above from the Cobar region, an understanding of the behaviour of Bi in the supergene environment can be made. If we consider the work done in Chapter 2 which assessed the solubility and stability of the minerals bismutite,
118 | P a g e bismoclite, and cannonite, we can determine a reasonable background concentration for the area. For this purpose, the phase diagram shown in Chapter 2 Figure 2.1 can be referenced.
ө Taking the ΔGf (298.2 K) values for bismutite, bismoclite and cannonite, found in
Chapter 2, and modelling them in equilibrium with every conceivable dissolved species then total dissolved Bi3+ can be evaluated. For this purpose, the equilibrium data of
ө Table 6.1 has been taken from the literature. In the calculations, a value for ΔGf
(Bi3+,aq,298.2K) is needed. Lovreček et al., (1985) give the standard electrode potential,
ө ө E , at 298.2 K for equation (4) as 0.3172 ±0.0006 V; this corresponds to ΔGf
(Bi3+,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 Bi3+ species.
The following is given as an example calculation for bismoclite. Lg K (298.2 K) for
ө equation (1) is derived from ΔGf data for constituent species given above and equation
(4) is the sum of (2) and (3).
Bi3+(aq) + 3e- ⇋ Bi(s) (1)
BiOCl(s) + 2H+(aq) ⇋ Bi3+(aq) + Cl-(aq) + H2O(l) lg K = -7.99 (2)
3+ 2+ + Bi (aq) + H2O(l) ⇋ BiOH (aq) + H (aq) lg K = -1.11 (3)
BiOCl(s) + H+(aq) ⇋ BiOH2+(aq) + Cl-(aq) lg K = -9.10 (4)
119 | P a g e
Therefore, we can start to model specific sites based on the reported minerals from specific regional or localised areas to define total dissolved bismuth values in any given area.
Inspection of the data from Tables 6.2 to 6.5 shows that the maximum Bi concentration in groundwater in equilibrium with the secondary Bi minerals at pH 5 is about 10-8 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 2.0 ppb. As a(Cl-) increases, total solution Bi is depressed further. The presence of less soluble phases will have an impact and also serve to limit
Bi solution levels. 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.
120 | P a g e
-3.5 - -1 Table 6.2: Total bismuth in solution at equilibrium with cannonite, bismoclite and bismutite Saline Water p(CO2) = 10 , activity of Cl = 10 2- --3 -13 and activity of SO4 = 10 (Saline) (absence of data refers to cases when the calculated activity is less than 10 ). pH Species 0 1 2 3 4 5 6 7 8 9 10 11 BiOH2+ 7.78E-09 7.78E-10 7.78E-11 7.78E-12 7.78E-13
+ Bi(OH)2 5.13E-11 5.13E-11 5.13E-11 5.13E-11 5.13E-11 5.13E-11 5.13E-11 5.13E-11 5.13E-11 5.13E-11 2.90E-12 2.90E-13 Bi(OH) 3.57E-07 3.57E-07 3 Bi(OH) - 7.92E-13 7.92E-11 4.50E-10 4.50E-09 4 Bi (OH) 6+ 6 22 Bi (OH) 7+ 9 20 Bi (OH) 6+ 9 21 BiCl2+ 2.56E-06 2.56E-08 2.56E-10 2.56E-12
BiCl + 3.23E-06 3.23E-08 3.23E-10 3.23E-12 2 BiCl 2.57E-04 2.57E-06 2.57E-08 2.57E-10 2.57E-12 3 BiCl - 1.28E-05 1.28E-07 1.28E-09 1.28E-11 1.28E-13 4 BiCl 2- 5.12E-06 5.12E-08 5.12E-10 5.12E-12 5 BiCl 3- 4.07E-07 4.07E-09 4.07E-11 4.07E-13 6 BiSO + 1.02E-10 1.02E-12 4 Bi(SO ) - 2.62E-10 2.62E-12 4 2 Bi(SO ) 3- 4.15E-10 4.15E-12 4 3 Bi(SO ) 5- 1.99E-11 1.99E-13 4 4 Bi3+ 1.02E-07 1.02E-09 1.02E-11 1.02E-13
Σ 2.81E-04 2.81E-06 2.82E-08 3.40E-10 5.49E-11 5.14E-11 5.13E-11 5.13E-11 5.21E-11 1.31E-10 3.58E-07 3.62E-07
121 | P a g e
-2.5 - -1 Table 6.3: Total bismuth in solution at equilibrium with cannonite, bismoclite and bismutite Saline Water p(CO2) = 10 , activity of Cl = 10 2- -3 -13 and activity of SO4 = 10 (Saline) (absence of data refers to cases when the calculated activity is less than 10 ). pH Species 0 1 2 3 4 5 6 7 8 9 10 11 BiOH2+ 7.78E-09 7.78E-10 7.78E-11 7.78E-12 7.78E-13
+ Bi(OH)2 5.13E-11 5.13E-11 5.13E-11 5.13E-11 5.13E-11 5.13E-11 5.13E-11 5.13E-11 5.13E-11 2.90E-11 2.90E-12 2.90E-13 Bi(OH) 3.57E-07 3.57E-07 3.57E-07 3 Bi(OH) - 7.92E-13 4.50E-11 4.50E-10 4.50E-09 4 Bi (OH) 6+ 6 22 Bi (OH) 7+ 9 20 Bi (OH) 6+ 9 21 BiCl2+ 2.56E-06 2.56E-08 2.56E-10 2.56E-12
BiCl + 3.23E-06 3.23E-08 3.23E-10 3.23E-12 2 BiCl 2.57E-04 2.57E-06 2.57E-08 2.57E-10 2.57E-12 3 BiCl - 1.28E-05 1.28E-07 1.28E-09 1.28E-11 1.28E-13 4 BiCl 2- 5.12E-06 5.12E-08 5.12E-10 5.12E-12 5 BiCl 3- 4.07E-07 4.07E-09 4.07E-11 4.07E-13 6 BiSO + 1.02E-10 1.02E-12 4 Bi(SO ) - 2.62E-10 2.62E-12 4 2 Bi(SO ) 3- 4.15E-10 4.15E-12 4 3 Bi(SO ) 5- 1.99E-11 1.99E-13 4 4 Bi3+ 1.02E-07 1.02E-09 1.02E-11 1.02E-13
Σ 2.81E-04 2.81E-06 2.82E-08 3.40E-10 5.49E-11 5.14E-11 5.13E-11 5.13E-11 5.21E-11 3.57E-07 3.58E-07 3.62E-07
122 | P a g e
-3.5 - -4 Table 6.4: Total bismuth in solution at equilibrium with cannonite, bismoclite and bismutite Saline Water p(CO2) = 10 , activity of Cl = 10 2- -3 -13 and activity of SO4 = 10 (fresh) (absence of data refers to cases when the calculated activity is less than 10 ). pH
Species 0 1 2 3 4 5 6 7 8 9 10 11 BiOH2+ 7.78E-06 7.78E-07 7.78E-08 7.78E-09 7.78E-10 7.78E-11 7.78E-12 1.37E-13
+ Bi(OH)2 5.13E-08 5.13E-08 5.13E-08 5.13E-08 5.13E-08 5.13E-08 5.13E-08 9.18E-09 9.18E-10 9.18E-11 9.18E-12 9.18E-13 Bi(OH) 6.29E-13 1.13E-06 1.13E-06 1.13E-06 1.13E-06 1.13E-06 3 Bi(OH) - 1.42E-12 1.42E-11 1.42E-10 1.42E-09 1.42E-08 4 Bi (OH) 6+ 6 22 Bi (OH) 7+ 9 20 Bi (OH) 6+ 9 21 BiCl2+ 2.56E-06 2.56E-08 2.56E-10 2.56E-12
BiCl + 3.23E-09 3.23E-11 3.23E-13 2 BiCl 2.57E-10 2.57E-12 3 BiCl - 4 BiCl 2- 5 BiCl 3- 6 BiSO + 1.02E-07 1.02E-09 1.02E-11 1.02E-13 4 Bi(SO ) - 2.62E-07 2.62E-09 2.62E-11 2.62E-13 4 2 Bi(SO ) 3- 4.15E-07 4.15E-09 4.15E-11 4.15E-13 4 3 Bi(SO ) 5- 1.99E-08 1.99E-10 1.99E-12 4 4 Bi3+ 1.02E-04 1.02E-06 1.02E-08 1.02E-10 1.02E-12
Σ 1.13E-04 1.88E-06 1.40E-07 5.92E-08 5.21E-08 5.14E-08 5.13E-08 1.14E-06 1.13E-06 1.13E-06 1.13E-06 1.14E-06
123 | P a g e
-2.5 - -4 Table 6.5: Total bismuth in solution at equilibrium with cannonite, bismoclite and bismutite Saline Water p(CO2) = 10 , activity of Cl = 10 2- -3 -13 and activity of SO4 = 10 (fresh) (absence of data refers to cases when the calculated activity is less than 10 ). pH
Species 0 1 2 3 4 5 6 7 8 9 10 11 BiOH2+ 7.78E-06 7.78E-07 7.78E-08 7.78E-09 7.78E-10 7.78E-11 4.33E-12
+ Bi(OH)2 5.13E-08 5.13E-08 5.13E-08 5.13E-08 5.13E-08 5.13E-08 2.90E-08 2.90E-09 2.90E-10 2.90E-11 2.90E-12 2.90E-13 Bi(OH) 6.29E-13 3.57E-07 3.57E-07 3.57E-07 3.57E-07 3.57E-07 3.57E-07 3 Bi(OH) - 4.50E-13 4.50E-12 4.50E-11 4.50E-10 4.50E-09 4 Bi (OH) 6+ 6 22 Bi (OH) 7+ 9 20 Bi (OH) 6+ 9 21 BiCl2+ 2.56E-06 2.56E-08 2.56E-10 2.56E-12
BiCl + 3.23E-09 3.23E-11 3.23E-13 2 BiCl 2.57E-10 2.57E-12 3 BiCl - 4 BiCl 2- 5 BiCl 3- 6 BiSO + 1.02E-07 1.02E-09 1.02E-11 1.02E-13 4 Bi(SO ) - 2.62E-07 2.62E-09 2.62E-11 2.62E-13 4 2 Bi(SO ) 3- 4.15E-07 4.15E-09 4.15E-11 4.15E-13 4 3 Bi(SO ) 5- 1.99E-08 1.99E-10 1.99E-12 4 4 Bi3+ 1.02E-04 1.02E-06 1.02E-08 1.02E-10 1.02E-12
Σ 1.13E-04 1.88E-06 1.40E-07 5.92E-08 5.21E-08 5.14E-08 3.86E-07 3.60E-07 3.58E-07 3.57E-07 3.58E-07 3.62E-07
124 | P a g e
6.6 BISMUTH MODEL FOR THE NEW ENGLAND REGION
This thesis has previously mentioned the Kingsgate region of Northern NSW and its reported mineralogy has been outlined in Chapter 1, Appendix A and Chapter 4.
Therefore, in this example we would need to consider and impose a number of limits to provide an appropriate summation on the solubility of Bi3+. For the pH conditions found in the Kingsgate regolith we find that 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). Also, the soils covering mineralised areas, in this case they are predominantly shallow, with an umbric
A horizon formed over acid siliceous rocks.
Inspection of the data from Tables 6.6 to 6.9 shows that the maximum Bi concentration in groundwater in equilibrium with the secondary Bi minerals koechlinite, bismoclite and bismutite at pH 5 is about 10-9 M (ignoring activity corrections). This in turn corresponds to a total solution Bi load of only 0.2 ppb. As a(Cl-) increases, total solution Bi is depressed further at 10-11M and is limited to 2.0 ppt. Put simply, the rate of dissolution of Bi minerals in the New England region and chemical dispersion of the element in the regolith is predicted to be very slow in comparison with most base metals. Therefore we can conclude that bismuth is not very mobile in the supergene environment. The mineralogical evidence and experimental solubility evidence demonstrates this and, in the context of exploration geochemistry of eastern Australia, has largely been untested as the use of Bi and Mo in these environment as pathfinders are of little to no use on a large-scale regional pathfinder. However, Bi would be useful as a localised pathfinder.
125 | P a g e
-2.5 - -1 Table 6.6: Total bismuth in solution at equilibrium with koechlinite, bismoclite and bismutite Saline Water p(CO2) = 10 , activity of Cl = 10 2- -4 2- -6 -13 activity of SO4 = 10 and activity of WO4 = 10 (absence of data refers to cases when the calculated activity is less than 10 ). pH
Species 0 1 2 3 4 5 6 7 8 9 10 11 BiOH2+ 7.78E-09 7.78E-10 7.78E-11 7.78E-12 7.78E-13
+ Bi(OH)2 5.13E-11 5.13E-11 5.13E-11 5.13E-11 5.13E-11 5.13E-11 5.13E-11 5.13E-11 5.13E-11 2.90E-11 2.90E-12 2.90E-13
Bi(OH)3 3.57E-07 3.57E-07 3.57E-07
- Bi(OH)4 7.92E-13 4.50E-11 4.50E-10 4.50E-09
6+ Bi6(OH)22
7+ Bi9(OH)20
6+ Bi9(OH)21
BiCl2+ 2.56E-06 2.56E-08 2.56E-10 2.56E-12
+ BiCl2 3.23E-06 3.23E-08 3.23E-10 3.23E-12
BiCl3 2.57E-04 2.57E-06 2.57E-08 2.57E-10 2.57E-12
- BiCl4 1.28E-05 1.28E-07 1.28E-09 1.28E-11 1.28E-13
2- BiCl5 5.12E-06 5.12E-08 5.12E-10 5.12E-12
3- BiCl6 4.07E-07 4.07E-09 4.07E-11 4.07E-13
+ 1.02E-10 1.02E-12 BiSO4
- 2.62E-10 2.62E-12 Bi(SO4)2
3- 4.15E-10 4.15E-12 Bi(SO4)3
5- 1.99E-11 1.99E-13 Bi(SO4)4
Bi3+ 1.02E-07 1.02E-09 1.02E-11 1.02E-13 Σ 2.81E-04 2.81E-06 2.82E-08 3.40E-10 5.49E -11 5.14E -11 5.13E -11 5.13E -11 5.21E -11 3.57E -07 3.58E -07 3.62E -07
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-3.5 - -1 Table 6.7: Total bismuth in solution at equilibrium with koechlinite, bismoclite and bismutite Saline Water p(CO2) = 10 , activity of Cl = 10 2- -4 2- -6 -13 activity of SO4 = 10 and activity of WO4 = 10 (absence of data refers to cases when the calculated activity is less than 10 ). pH Species 0 1 2 3 4 5 6 7 8 9 10 11 BiOH2+ 7.78E-09 7.78E-10 7.78E-11 7.78E-12 7.78E-13
+ Bi(OH)2 5.13E-11 5.13E-11 5.13E-11 5.13E-11 5.13E-11 5.13E-11 5.13E-11 5.13E-11 5.13E-11 5.13E-11 9.18E-12 9.18E-13 Bi(OH) 1.13E-06 1.13E-06 3 Bi(OH) - 7.92E-13 7.92E-11 1.42E-09 1.42E-08 4 Bi (OH) 6+ 6 22 Bi (OH) 7+ 9 20 Bi (OH) 6+ 9 21 BiCl2+ 2.56E-06 2.56E-08 2.56E-10 2.56E-12
BiCl + 3.23E-06 3.23E-08 3.23E-10 3.23E-12 2 BiCl 2.57E-04 2.57E-06 2.57E-08 2.57E-10 2.57E-12 3 BiCl - 1.28E-05 1.28E-07 1.28E-09 1.28E-11 1.28E-13 4 BiCl 2- 5.12E-06 5.12E-08 5.12E-10 5.12E-12 5 BiCl 3- 4.07E-07 4.07E-09 4.07E-11 4.07E-13 6 BiSO + 1.02E-10 1.02E-12 4 Bi(SO ) - 2.62E-10 2.62E-12 4 2 Bi(SO ) 3- 4.15E-10 4.15E-12 4 3 Bi(SO ) 5- 1.99E-11 1.99E-13 4 4 Bi3+ 1.02E-07 1.02E-09 1.02E-11 1.02E-13
Σ 2.81E-04 2.81E-06 2.82E-08 3.40E-10 5.49E-11 5.14E-11 5.13E-11 5.13E-11 5.21E-11 1.31E-10 1.13E-06 1.14E-06
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-2.5 - -4 Table 6.8: Total bismuth in solution at equilibrium with koechlinite, bismoclite and bismutite Fresh Water p(CO2) = 10 , activity of Cl = 10 2- -4 2- -6 -13 activity of SO4 = 10 and activity of WO4 = 10 (absence of data refers to cases when the calculated activity is less than 10 ). pH
Species 0 1 2 3 4 5 6 7 8 9 10 11 BiOH2+ 7.78E-06 7.78E-07 7.78E-08 5.60951E-09 1.77388E-10 5.54607E-12 5.54607E-13
+ Bi(OH)2 5.13E-08 5.13E-08 5.13E-08 3.68383E-08 1.16493E-08 3.64216E-09 3.64216E-09 2.90E-09 2.90E-10 2.90E-11 2.90E-12 2.90E-13 Bi(OH) 6.29E-13 1.43307E-11 1.43307E-11 4.48051E-09 4.48051E-08 3.57E-07 3.57E-07 3.57E-07 3.57E-07 3.57E-07 3 Bi(OH) - 4.50E-13 4.50E-12 4.50E-11 4.50E-10 4.50E-09 4 Bi (OH) 6+ 6 22 Bi (OH) 7+ 9 20 Bi (OH) 6+ 9 21 BiCl2+ 2.56E-06 2.56E-08 2.56E-10 1.84651E-12
BiCl + 3.23E-09 3.23E-11 3.23E-13 2 BiCl 2.57E-10 2.57E-12 3 BiCl - 4 BiCl 2- 5 BiCl 3- 6 BiSO + 1.02E-07 1.02E-09 1.02E-11 2.37531E-13 4 Bi(SO ) - 2.62E-07 2.62E-09 2.62E-11 1.8851E-13 4 2 Bi(SO ) 3- 4.15E-07 4.15E-09 4.15E-11 2.9902E-13 4 3 Bi(SO ) 5- 1.99E-08 1.99E-10 1.99E-12 4 4 Bi3+ 1.02E-04 1.02E-06 1.02E-08 7.35383E-11 2.32548E-13
Σ 1.13E-04 1.88E-06 1.40E-07 4.25382E-08 1.18412E-08 8.12822E-09 4.84478E-08 3.60E-07 3.58E-07 3.57E-07 3.58E-07 3.62E-07
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-.3.5 - -4 Table 6.9: Total bismuth in solution at equilibrium with koechlinite, bismoclite and bismutite Fresh Water p(CO2) = 10 , activity of Cl = 10 2- -4 2- -6 -13 activity of SO4 = 10 and activity of WO4 = 10 (absence of data refers to cases when the calculated activity is less than 10 ). pH
Species 0 1 2 3 4 5 6 7 8 9 10 11 2+ 7.78E-06 7.78E-07 7.78E-08 2.49041E-10 2.49041E-11 2.49041E-12 2.49041E-13 BiOH + Bi(OH)2 5.13E-08 5.13E-08 5.13E-08 1.60931E-09 1.60931E-09 1.60931E-09 1.60931E-09 1.60931E-09 9.18E-10 9.18E-11 9.18E-12 9.18E-13 6.29E-13 1.97973E-11 1.97973E-10 1.97973E-09 1.97973E-08 1.97973E-07 1.13E-06 1.13E-06 1.13E-06 1.13E-06 Bi(OH)3 - 2.49485E-13 1.42E-11 1.42E-10 1.42E-09 1.42E-08 Bi(OH)4 6+ Bi6(OH)22 7+ Bi9(OH)20 6+ Bi9(OH)21 2+ 2.56E-06 2.56E-08 2.56E-10 BiCl + 3.23E-09 3.23E-11 3.23E-13 BiCl2 2.57E-10 2.57E-12 BiCl3 - BiCl4 2- BiCl5 3- BiCl6 + 1.02E-07 1.02E-09 1.02E-11 3.28141E-13 BiSO4 - 2.62E-07 2.62E-09 2.62E-11 Bi(SO4)2 3- 4.15E-07 4.15E-09 4.15E-11 Bi(SO4)3 5- 1.99E-08 1.99E-10 1.99E-12 Bi(SO4)4 3+ 1.02E-04 1.02E-06 1.02E-08 Bi Σ 1.13E-04 1.88E-06 1.40E-07 1.87858E-09 1.83219E-09 3.59153E-09 2.14069E-08 1.99583E-07 1.13E-06 1.13E-06 1.13E-06 1.14E-06
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6.7 CONCLUSION
In conclusion, the chemical rationale for bismuth’s geochemically immobile nature can be understood in the weathering environment. This work explains the differential leaching and mobility of Bi the Kingsgate and Cobar deposits. The model outlined above explains the limited mobility at Kingsgate and suggests that much of the New England
Orogen remains untested as the values obtained in this work are found to be lower than the reported arbitrary values found in the literature (MacDuff and Snow, 1971; MacDuff and
Zerwick 1971a; MacDuff and Zerwick 1971b; MacDuff and Zerwick 1972; Siegal, 1974;
Rose et al., 1979; Levinson, 1980; Plant et al., 1989; Plant et al.,1991; Filella, 2010). Also, the use of conventional Atomic Absorption Spectroscopy (AAS) is not a useful analytical method for the determination of Bi at low levels. This is important given the data above concerning the distribution of the element in rocks, soils and natural waters. Even though modern ICP-OES or ICP-MS and other methods are both accurate and precise to much lower levels (Filella, 2010; Gholivand and Romiani, 2006) and hydride generation methods have greatly increased the sensitivity of Bi determinations using AAS (Campbell, 1992) these techniques would still be inadequate in some circumstances.
This work also highlights 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 localised pathfinder element in geochemical exploration when it is present in significant amounts in primary ores. Cobar- style mineralisation is known to contain 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
130 | P a g e 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). This conclusion applies to exploration programs carried-out in the past with the same kinds of analytical constraints. The model developed above requires that the results be revaluated and this model should be taken into consideration for future planning and development of geochemical exploration strategies along the East Coast of Australia.
6.7 REFERENCES
Andrews, E.C. (1911) Cobar Copper and Gold Field. Part I. New South Wales Department
of Mines, Sydney.
Barreca, D., Morazzoni, F., Rizzi, G.A, Scotti, R. and Tondello, E. (2001) Molecular oxygen
interaction with Bi2O=: a spectroscopic and spectromagnetic investigation. Physical
Chemistry and Chemical Physics, 3, 1743-1749.
Berthelsen, R.R., (2004) Exploration in the Cobar Gold Field: A 2004 Perspective. In:
McQueen, K.G. and Scott, K.M. (2004) Exploration Field Workshop Cobar Region
2004,Proceedings. CRC LEME Report, Cooperative Research Centre for Landscape
Environments and Mineral Exploration, Perth WA. 5-9.
Campbell, A.D. (1992) A critical survey of hydride generation techniques in atomic
spectroscopy. Pure and Applied Chemistry, 64, 227-244.
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Cox, J.D., Wagman, D.D. and Medvedev, V.A. (1989) CODATA Key Values for
Thermodynamics. Hemisphere Press, New York.
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.
Fedorov, V.A., Kalosh, T.N., Chernikova, G.E. and Mironov, V.E. (1971) Sulphato-
complexes of bismuth(III). Russian Journal of Physical Chemistry, 45, 106.
Filella, M. (2010) How reliable are environmental data on 'orphan' elements? The case of
bismuth concentrations in surface waters. Journal of Environmental Monitoring, 12, 90-
109.
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.
Gilligan, L.B. & Byrnes, J.G. (1994) Cobar 1:250 000 Metallogenic Map SH/55-14: Metal
Study and Mineral Deposit Data Sheets. Geological Survey of New South Wales,
Sydney
Kaye, G.W.C. and Laby, T.H. (1995) Tables of Physical and Chemical Constants. 16th
Edition, Longman, London, Section 3.10.5.
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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
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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.
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.
Levinson, A.A., (1980) Introduction to Exploration Geochemistry: The Supplement, Applied
Publishing Ltd, Wilmette, USA, 1980, 615-924.
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.
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Pillans, B., Tonui, E. and Indurm, M. (1999) Paleomagnetic dating and weathered regolith.
In: Taylor, G. and Pain, C. (Eds) Approaches to an Old Continent, Proceedings of the
Regolith 98 Conference, Kalgoorlie, CRC LEME, Perth, 237-242.
Plant, J.A., Breward, N., Forrest, M.D. and Smith, R.T. (1989) The gold pathfinder elements
As, Sb and Bi - their distribution and significance in the southwest Highlands of Scotland.
Transactions of the Institution of Mining and Metallurgy, 98, B91-101.
Plant, J.A., Cooper, D.C., Green, P.M., Reedman, A.J. and Simpson, P.R. (1991) Regional
distribution of As, Sb and Bi in the Grampian Highlands of Scotland and English Lake
District: implications for gold metallogeny. Transactions of the Institution of Mining and
Metallurgy, 100, B135-147.
MacDuff, R. and Snow, A. (1971) Quarterly Report Period to 8th January 1971, EL208,
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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)
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MacDuff, R. and Zerwick, J. (1971b) EL208, Quarterly Report Period to 8th October 1971,
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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.
McClatchie, L. (1971) Base metal mineralisation at Mineral Hill, central Western New South
Wales. Geological Survey of New South Wales, Sydney.
McKinnon, A.R., Sharpe, J.L. & Williams, P.A. (2005) Other notable mineral occurrences in
the Cobar region. Australian Journal of Mineralogy, 11, 117-121.
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Survey of New South Wales, Sydney.
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.
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Academic Press, New York, N.Y., pp. 490--517.
Smith, R.M. and Martell, A.E., 1976: Critical Stability Constants. 4. Inorganic Complexes.
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J.A. (Eds) The Cobar Mineral Field – A 1996 Perspective, Australasian Institute of
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Stegman, C.L. & Reynolds, I. (2005) Primary mineralisation in Cobar deposits, with
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Metallogenic Study and Mineral Deposit Data Sheets. Geological Survey of New South
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bismuth carbonates. Canadian Journal of Chemistry, 62, 2863-2873. van der Lee, J. and Lomenech, C. (2004) Towards a common thermodynamic database for
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Appendix A
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
Dundee D24224 Koechlinite D28509 Koechlinite, quartz D28510 Bismite, bismutite D28511 Koechlinite, bismutite D28512 As for D28511 D35450 Zavaritskite, bismite, bismutite, koechlinite D35450 Bismutite.
Elsmore D15631 Bismoclite D28050 Bismoclite Emmaville D18210 Russellite, bismutite
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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, bismutite. D7194 Koechlinite, bismutite D22004 Bismutite D30956 Bismutite, koechlinite. D31339 Koechlinite D31340 Wulfenite, koechlinite, bismutite D31341 Wulfenite, koechlinite, bismutite D31343 Bismutite, preisingerite D31420 Bismutite. D38036 Bismutite, chekhovichite, smrkovecite M30035 Bismutite, bismite M47205 Ferrimolybdite
Nanima D18931 Bismutite D25033 Bismutite.
Mt Gipps D15637 Bismutite, kettnerite
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Mt Razorback D35482 Bismutite
Murrumbateman D30998 Bismutite Torrington D18209 Bismutite, russellite D28513 Bismutite D29744 Bismutite, russellite 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
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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 with minor quartz and amorphous iron oxides. Wolfram Camp D31451 Koechlinite D31452 Koechlinite, bismutite
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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
Everton M38367 Ferrimolybdite M40860 Ferrimolybdite; XRDMV M42790 Ferrimolybdite M47686 Mendozavilite Gombianbar Creek M274 Bismutite Maldon
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M7552 Bismutite M15402 Bismutite
Mt Moliagul M39540 Ferrimolybdite M40723 As for M39540
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 Mt Magnet D36109 Bismutite D36110 Bismutite
Poona M49672 Russellite, bismutite; XRDMV Warriedar M35505 Ferrimolybdite
aThese were determined by XRD during the course of this study and are in addition to those previously reported by Rankin (2001, 2002) 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).
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