DOCSLIB.ORG

Growth Oscillatory Zoning in Erythrite, Ideally Co3(Aso4)28H2O

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Growth Oscillatory Zoning in Erythrite, Ideally Co3(Aso4)28H2O minerals Article Growth Oscillatory Zoning in Erythrite, Ideally Co3(AsO4)2·8H2O: Structural Variations in Vivianite-Group Minerals Sytle M. Antao * ID and Inayat Dhaliwal Department of Geoscience, University of Calgary, Calgary, AB T2N 1N4, Canada; [email protected] * Correspondence: [email protected]; Tel.: +1-403-220-3083 Received: 11 July 2017; Accepted: 30 July 2017; Published: 2 August 2017 Abstract: The crystal structure of an oscillatory zoned erythrite sample from Aghbar mine, Bou Azzer, Morocco, was refined using synchrotron high-resolution powder X-ray diffraction (HRPXRD) data, Rietveld refinement, space group C2/m, and Z = 2. The crystal contains two sets of oscillatory zones that appear to have developed during epitaxial growth. The unit-cell parameters obtained are a = 10.24799(3) Å, b = 13.42490(7) Å, c = 4.755885(8) Å, b = 105.1116(3)◦, and V = 631.680(4) Å3. The empirical formula for erythrite, obtained with electron-probe micro-analysis (EPMA), is [Co2.78Zn0.11Ni0.07Fe0.04]∑3.00(AsO4)2·8H2O. Erythrite belongs to the vivianite-type structure that contains M1O2(H2O)4 octahedra and M22O6(H2O)4 octahedral dimers that are linked by TO4 (T5+ = As or P) tetrahedra to form complex layers parallel to the (010) plane. These layers are connected by hydrogen bonds. The average <M1–O>[6] = 2.122(1) Å and average <M2–O>[6] = 2.088(1) Å. With space group C2/m, there are two solid solutions: M3(AsO4)2·8H2O and M3(PO4)2·8H2O where M2+ = Mg, Fe, Co, Ni, or Zn. In these As- and P-series, using data from this study and from the literature, we find that their structural parameters evolve linearly with V and in a nearly parallel manner despite of the large difference in size between P5+ (0.170 Å) and As5+ (0.355 Å) cations. Average <T–O>[4], <M1–O>[6], and <M2–O>[6] distances increase linearly with V. The average <As–O> distance is affected by M atoms, whereas the average <P–O> distance is unaffected because it contains shorter and stronger P–O bonds. Although As- and P-series occur naturally, there is no structural reason why similar V-series vivianite-group minerals do not occur naturally or cannot be synthesized. Keywords: erythrite; vivianite-group minerals; structure; chemistry; oscillatory zones; synchrotron high-resolution powder X-ray diffraction (HRPXRD); Rietveld refinement 1. Introduction Erythrite, ideally Co3(AsO4)2·8H2O, is a member of the vivianite-group minerals with general 2+ 5+ formula M3(TO4)2·8H2O where M = Mg, Fe, Co, Ni, or Zn and T = P or As. Because of the difference in size of P (0.170 Å) and As (0.355 Å) atoms, two solid solutions occur with different chemical evolution and structural characteristics. Solid solutions do not occur between the two separate P- and As- series. Both series have monoclinic space group C2/m with Z = 2. In addition to the above two solid solutions, there is no structural reason for the existence of a third series with V5+ (0.335 Å) cation, as in the lead-apatite series [1–3]. V-series vivianite-group minerals have not been found in nature because another phase may be more stable. However, it would be of interest to synthesize V-series vivianite materials. Because the P–O bond is short and strong, the interstitial M atoms are unlikely to have any significantly effect on the average <P–O> distance, whereas the average <As–O> distance is longer, so the As–O bond is weaker and is affected by the M atoms. This observation is confirmed using data from this study and the literature (Table1). Minerals 2017, 7, 136; doi:10.3390/min7080136 www.mdpi.com/journal/minerals Minerals 2017, 7, 136 2 of 13 Table 1. Structural data for vivianite-group minerals with space group C2/m (listed with increasing V in each series). Mineral Composition a/Å b/Å c/Å b/◦ V/Å3 <M1–O> <M2–O> <T–O> Reference As-series M3(AsO4)2·8H2O: M = annabergite [Ni2.48Mg0.50Fe0.02] 10.179 13.309 4.725 105.00 618.2 2.086 2.073 1.691 [4] cabrerite [Ni2.2Mg0.7Fe0.1]3 10.211 13.335 4.728 104.97 621.9 2.086 2.074 1.690 [5] köttigite [Zn2.44Co0.42Ni0.14] 10.241 13.405 4.757 105.21 630.2 2.115 2.100 1.682 [6] Mg-erythrite [Co2.16Mg0.60Ni0.24] 10.187 13.470 4.755 104.97 630.3 2.116 2.095 1.693 [7] hörnesite Mg3 10.26 13.44 4.74 104.90 631.6 - - - [8] erythrite [Co2.78Zn0.11Ni0.07Fe0.04] 10.248 13.425 4.756 105.11 631.7 2.122 2.088 1.710 This study syn. hörnesite-annabergite ss [Mg2.5Ni0.5] 10.257 13.421 4.753 105.08 631.7 2.115 2.114 1.714 [9] hörnesite Mg3 10.279 13.455 4.749 105.12 634.1 - - - [10] erythrite [Co2.01Fe0.74Ni0.25] 10.251 13.447 4.764 104.98 634.4 2.116 2.106 1.694 [4] köttigite-parasymplesite ss [Fe1.62Zn1.38] 10.342 13.484 4.776 105.31 642.3 2.134 2.101 1.696 [11] parasymplesite Fe3 10.35 13.52 4.79 104.90 647.7 - - - [12] P-series M3(PO4)2·8H2O: M = syn. pakhomovskyite Co3 10.021 13.331 4.673 104.90 603.3 2.112 2.102 1.543 [13] pakhomovskyite Co2.38Mg0.38Mn0.17Ni0.04Fe0.03 10.034 13.341 4.670 105.02 603.8 - - - [14] syn. Mg-vivianite Mg3 10.034 13.407 4.657 105.09 604.9 2.094 2.085 1.545 [15] 2+ 3+ bari´cite [Mg1.70Fe 1.19Fe 0.11] 10.085 13.39 4.671 104.96 609.4 2.132 2.100 1.549 [16] vivianite Fe3 10.086 13.441 4.703 104.27 617.9 2.152 2.132 1.542 [17] vivianite [Fe2.75Zn0.25] 10.083 13.468 4.718 104.47 620.3 2.151 2.134 1.543 [18] vivianite Fe3 10.116 13.473 4.706 104.33 621.5 2.152 2.124 1.544 [18] vivianite [Fe2.88Mg0.12] 10.1 13.494 4.709 104.24 622.1 2.166 2.134 1.546 [18] syn. = synthetic, ss = solid solution. Minerals 2017, 7, 136 3 of 13 The structure of vivianite, ideally Fe3(PO4)2·8H2O, was determined by Mori and Ito [19] and subsequently refined by others [17,20,21]. Other vivianite-type materials were structurally investigated: parasymplesite, Fe3(AsO4)2·8H2O[19]; köttigite, ideally Zn3(AsO4)2·8H2O[6]; cabrerite, (Ni,Mg)3(AsO4)2·8H2O, a Mg-rich variety of annabergite [5]; synthetic Mg3(PO4)2·8H2O[15]; synthetic Co3(PO4)2·8H2O[13]. The structural parameters of these minerals are summarized in Table1. Arsenate minerals from the vivianite group usually occur as secondary minerals in the oxidation zones of some arsenic-rich hydrothermal base-metal mineral deposits. It is important to study the chemistry of the vivianite-group minerals because of their significance in mineralogy and proton super-ionic conduction, especially the hydrogen-bonding geometry [11]. The study examines the crystal chemistry of an oscillatory zoned erythrite crystal using Rietveld structure refinement, synchrotron high-resolution powder X-ray diffraction (HRPXRD) data, and electron-probe micro-analyzer (EPMA) data. Solid solutions for the As- and P-series are also examined using data from this study and the literature. Similar experimental techniques were used to examine other minerals [22–26]. 2. Experimental Methods 2.1. Sample Description and Electron-Probe Micro-Analyzer (EPMA) Experiments were performed on a sample of erythrite from Aghbar mine, Bou Azzer, Morocco. The sample contains euhedral crystals that are well-developed with excellent faces. The prismatic crystals are elongated along the [001] direction and flattened on the (010) plane. Quantitative chemical compositions, back-scattered electron (BSE) image, and elemental maps were collected with a JEOL JXA-8200 WD-ED electron-probe micro-analyzer (EPMA). The JEOL operating program on a Solaris platform was used for ZAF correction and data reduction. The wavelength- dispersive (WD) operating conditions were 15 kV accelerating voltage, 20 nA beam current, and 5 µm beam diameter. The standards used were cobalt (CoKα), hornblende (FeKα), nickel oxide (NiKα), zinc oxide (ZnKα), almandine-pyrope (MgKα), gallium arsenide (AsKα), apatite (PKα), and barite (SKα). The results of the average EPMA analyses (from 11 points) are listed in Table2 and results in the empirical formula [Co2.78Zn0.11Ni0.07Fe0.04]∑3.00(AsO4)2·8H2O. The BSE image and elemental maps show two sets of crystal growth zones that occur as oscillatory features (Figure1). This chemical heterogeneity is also evident from the variations of the atoms from one spot to another (Figure2). Table 2. Chemical analyses for erythrite. As2O5 wt % 38.39 SO3 0.06 P2O5 0.00 CoO 34.89 ZnO 1.50 NiO 0.84 FeO 0.49 MgO 0.00 H2O 22.10 ∑ 98.25 As apfu 1.996 S 0.004 P 0.000 ∑(As,S,P) 2.000 Co 2.782 Zn 0.110 Ni 0.067 Fe 0.040 Mg 0.000 ∑(Co,Zn,Ni,Fe,Mg) 3.000 H2O 8.000 The atom per formula unit (apfu) were calculated on basis of 5 metal atoms. H2O was fixed to 8. The chemical formula is [Co2.78Zn0.11Ni0.07Fe0.04]∑3.00(AsO4)2·8H2O. Minerals 2017, 7, 136 4 of 13 Figure 1.
Load more

Recommended publications
  • Kinetics of Phosphorus Release from Vivianite, Hydroxyapatite, and Bone Char Influenced by Organic and Inorganic Compounds
    Article Kinetics of Phosphorus Release from Vivianite, Hydroxyapatite, and Bone Char Influenced by Organic and Inorganic Compounds Elisabeth Schütze, Stella Gypser * and Dirk Freese Faculty of Environment and Natural Sciences, Brandenburg University of Technology Cottbus-Senftenberg, Chair of Soil Protection and Recultivation, Konrad-Wachsmann-Allee 6, 03046 Cottbus, Germany; [email protected] (E.S.); [email protected] (D.F.) * Correspondence: [email protected] Received: 7 February 2020; Accepted: 12 March 2020; Published: 16 March 2020 Abstract: The availability of P is often insufficient and limited by accumulation in soils. This led to the necessity of solutions for the recovery as well as recycling of secondary P resources. Batch experiments were conducted with CaCl2 and citric acid to characterize P release kinetics from vivianite, hydroxyapatite, and bone char. While the P release during the CaCl2 treatment was so low that only vivianite and hydroxyapatite showed a slightly higher release with increasing CaCl2 concentration, the increase of dissolved P was more pronounced for citric acid. The application of citric acid resulted in a 32,190-fold higher P release for bone char. Fourier-transform infrared spectroscopic data suggested higher instability of hydroxyapatite than for bone char. The kinetic data showed that bone char, especially at a lower particle size, had a higher long-term P release than hydroxyapatite or vivianite. The suitability of hydroxyapatite and bone char as a poorly soluble, but sustainable P source is better than that of vivianite. However, the efficiency as a P fertilizer is also dependent on present soil P mobilization processes.
    [Show full text]
  • Download PDF About Minerals Sorted by Mineral Name
    MINERALS SORTED BY NAME Here is an alphabetical list of minerals discussed on this site. More information on and photographs of these minerals in Kentucky is available in the book “Rocks and Minerals of Kentucky” (Anderson, 1994). APATITE Crystal system: hexagonal. Fracture: conchoidal. Color: red, brown, white. Hardness: 5.0. Luster: opaque or semitransparent. Specific gravity: 3.1. Apatite, also called cellophane, occurs in peridotites in eastern and western Kentucky. A microcrystalline variety of collophane found in northern Woodford County is dark reddish brown, porous, and occurs in phosphatic beds, lenses, and nodules in the Tanglewood Member of the Lexington Limestone. Some fossils in the Tanglewood Member are coated with phosphate. Beds are generally very thin, but occasionally several feet thick. The Woodford County phosphate beds were mined during the early 1900s near Wallace, Ky. BARITE Crystal system: orthorhombic. Cleavage: often in groups of platy or tabular crystals. Color: usually white, but may be light shades of blue, brown, yellow, or red. Hardness: 3.0 to 3.5. Streak: white. Luster: vitreous to pearly. Specific gravity: 4.5. Tenacity: brittle. Uses: in heavy muds in oil-well drilling, to increase brilliance in the glass-making industry, as filler for paper, cosmetics, textiles, linoleum, rubber goods, paints. Barite generally occurs in a white massive variety (often appearing earthy when weathered), although some clear to bluish, bladed barite crystals have been observed in several vein deposits in central Kentucky, and commonly occurs as a solid solution series with celestite where barium and strontium can substitute for each other. Various nodular zones have been observed in Silurian–Devonian rocks in east-central Kentucky.
    [Show full text]
  • High-Temperature Thermomagnetic Properties of Vivianite Nodules
    EGU Journal Logos (RGB) Open Access Open Access Open Access Advances in Annales Nonlinear Processes Geosciences Geophysicae in Geophysics Open Access Open Access Natural Hazards Natural Hazards and Earth System and Earth System Sciences Sciences Discussions Open Access Open Access Atmospheric Atmospheric Chemistry Chemistry and Physics and Physics Discussions Open Access Open Access Atmospheric Atmospheric Measurement Measurement Techniques Techniques Discussions Open Access Open Access Biogeosciences Biogeosciences Discussions Open Access Open Access Clim. Past, 9, 433–446, 2013 Climate www.clim-past.net/9/433/2013/ Climate doi:10.5194/cp-9-433-2013 of the Past of the Past © Author(s) 2013. CC Attribution 3.0 License. Discussions Open Access Open Access Earth System Earth System Dynamics Dynamics Discussions High-temperature thermomagnetic properties of Open Access Open Access vivianite nodules, Lake El’gygytgyn, Northeast RussiaGeoscientific Geoscientific Instrumentation Instrumentation P. S. Minyuk1, T. V. Subbotnikova1, L. L. Brown2, and K. J. Murdock2 Methods and Methods and 1North-East Interdisciplinary Scientific Research Institute, Far East Branch of the Russian AcademyData Systems of Sciences, Data Systems Magadan, Russia Discussions Open Access 2 Open Access Department of Geosciences, University of Massachusetts, Amherst, USA Geoscientific Geoscientific Correspondence to: P. S. Minyuk ([email protected]) Model Development Model Development Received: 7 September 2012 – Published in Clim. Past Discuss.: 9 October 2012 Discussions Revised: 15 January 2013 – Accepted: 15 January 2013 – Published: 19 February 2013 Open Access Open Access Hydrology and Hydrology and Abstract. Vivianite, a hydrated iron phosphate, is abun- 1 Introduction Earth System Earth System dant in sediments of Lake El’gygytgyn, located in the Anadyr Mountains of central Chukotka, northeastern Rus- Sciences Sciences sia (67◦300 N, 172◦050 E).
    [Show full text]
  • Geochemistry, Mineralogy and Microbiology of Cobalt in Mining-Affected Environments
    minerals Article Geochemistry, Mineralogy and Microbiology of Cobalt in Mining-Affected Environments Gabriel Ziwa 1,2,*, Rich Crane 1,2 and Karen A. Hudson-Edwards 1,2 1 Environment and Sustainability Institute, University of Exeter, Penryn TR10 9FE, UK; [email protected] (R.C.); [email protected] (K.A.H.-E.) 2 Camborne School of Mines, University of Exeter, Penryn TR10 9FE, UK * Correspondence: [email protected] Abstract: Cobalt is recognised by the European Commission as a “Critical Raw Material” due to its irreplaceable functionality in many types of modern technology, combined with its current high-risk status associated with its supply. Despite such importance, there remain major knowledge gaps with regard to the geochemistry, mineralogy, and microbiology of cobalt-bearing environments, particu- larly those associated with ore deposits and subsequent mining operations. In such environments, high concentrations of Co (up to 34,400 mg/L in mine water, 14,165 mg/kg in tailings, 21,134 mg/kg in soils, and 18,434 mg/kg in stream sediments) have been documented. Co is contained in ore and mine waste in a wide variety of primary (e.g., cobaltite, carrolite, and erythrite) and secondary (e.g., erythrite, heterogenite) minerals. When exposed to low pH conditions, a number of such minerals are 2+ known to undergo dissolution, typically forming Co (aq). At circumneutral pH, such aqueous Co can then become immobilised by co-precipitation and/or sorption onto Fe and Mn(oxyhydr)oxides. This paper brings together contemporary knowledge on such Co cycling across different mining environments.
    [Show full text]
  • Raman and Infrared Spectroscopy of Arsenates of the Roselite and Fairfeldite Mineral Subgroups
    This may be the author’s version of a work that was submitted/accepted for publication in the following source: Frost, Ray (2009) Raman and infrared spectroscopy of arsenates of the roselite and fair- feldite mineral subgroups. Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, 71(5), pp. 1788-1794. This file was downloaded from: https://eprints.qut.edu.au/17596/ c Copyright 2009 Elsevier Reproduced in accordance with the copyright policy of the publisher. Notice: Please note that this document may not be the Version of Record (i.e. published version) of the work. Author manuscript versions (as Sub- mitted for peer review or as Accepted for publication after peer review) can be identified by an absence of publisher branding and/or typeset appear- ance. If there is any doubt, please refer to the published source. https://doi.org/10.1016/j.saa.2008.06.039 QUT Digital Repository: http://eprints.qut.edu.au/ Frost, Ray L. (2009) Raman and infrared spectroscopy of arsenates of the roselite and fairfieldite mineral subgroups. Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, 71(5). pp. 1788-1794. © Copyright 2009 Elsevier Raman and infrared spectroscopy of arsenates of the roselite and fairfieldite mineral subgroups Ray L. Frost• Inorganic Materials Research Program, School of Physical and Chemical Sciences, Queensland University of Technology, GPO Box 2434, Brisbane Queensland 4001, Australia. Abstract Raman spectroscopy complimented with infrared spectroscopy has been used to determine the molecular structure of the roselite arsenate minerals of the roselite and 2+ fairfieldite subgroups of formula Ca2B(AsO4)2.2H2O (where B may be Co, Fe , Mg, 2- Mn, Ni, Zn).
    [Show full text]
  • Cobalt Mineral Ecology
    American Mineralogist, Volume 102, pages 108–116, 2017 Cobalt mineral ecology ROBERT M. HAZEN1,*, GRETHE HYSTAD2, JOSHUA J. GOLDEN3, DANIEL R. HUMMER1, CHAO LIU1, ROBERT T. DOWNS3, SHAUNNA M. MORRISON3, JOLYON RALPH4, AND EDWARD S. GREW5 1Geophysical Laboratory, Carnegie Institution, 5251 Broad Branch Road NW, Washington, D.C. 20015, U.S.A. 2Department of Mathematics, Computer Science, and Statistics, Purdue University Northwest, Hammond, Indiana 46323, U.S.A. 3Department of Geosciences, University of Arizona, 1040 East 4th Street, Tucson, Arizona 85721-0077, U.S.A. 4Mindat.org, 128 Mullards Close, Mitcham, Surrey CR4 4FD, U.K. 5School of Earth and Climate Sciences, University of Maine, Orono, Maine 04469, U.S.A. ABSTRACT Minerals containing cobalt as an essential element display systematic trends in their diversity and distribution. We employ data for 66 approved Co mineral species (as tabulated by the official mineral list of the International Mineralogical Association, http://rruff.info/ima, as of 1 March 2016), represent- ing 3554 mineral species-locality pairs (www.mindat.org and other sources, as of 1 March 2016). We find that cobalt-containing mineral species, for which 20% are known at only one locality and more than half are known from five or fewer localities, conform to a Large Number of Rare Events (LNRE) distribution. Our model predicts that at least 81 Co minerals exist in Earth’s crust today, indicating that at least 15 species have yet to be discovered—a minimum estimate because it assumes that new minerals will be found only using the same methods as in the past. Numerous additional cobalt miner- als likely await discovery using micro-analytical methods.
    [Show full text]
  • Note on Lavendulan from Joachimstal, Bohemia
    TOURNAL XIINERALOG}CAL SOCIET'Y OF A]IERICA 29 NOTE ON LAVENDULAN FROM JOACHIMSTAL, BOHEMIA \Vrrrrnu F. Fosnac,l Llnited, Stotes National Museu,m Under the name lavendulan, Breithaupt2 described a mineral from Annaberg in the Erzgebirge' The mineral formed thin crusts of a lavender blue color and botryoidal structure. Sufficient material apparently was not available for a quantitative analysis but the blowpipe characteristics were determined by Plattner' The collection of Colonel Washington A. Roebling contains a specimen of lavendulan from Joachimstal which probably repre- sents the same mineral described by Breithaupt. It is entirely similar in general appearances and blowpipe characteristics to the Annaberg material. The lavendulan forms very thin crusts with botryoidal surlace upon a seam of qvartz in a mica schist. Its color is patent blue (Ridgeway) with a vitreous to waxy lustre. Although the crust appears amorphous, under the microscopeit is seento be made up of minute radiated fibers or plates. They are slightly pleochroic, the colors being patent to oxide blue. The plates are so small that the optical properties could not be determined with exactness' The followingconstants were measured: B: 1'715+ 005;t: l'725+003' Z is in the direction of the length of the fibers. The extinction is inclined to the length of the fibers. The mineral is distinctly made up of bands of varying composition and the indices of refraction show a corresponding variation. Breithaupt's mineral was essentially a hydrous cobalt arsenate with some copper and nickel. Before the blowpipe the mineral colored the flame light blue (arsenic) and fused easily to a mass that assumedcrystalline form upon cooling.
    [Show full text]
  • 30 the AMERICAN MINERALOGIST the Optical Properties of The
    30 THE AMERICAN MINERALOGIST The optical properties of the lavendulan are similar to those of erythrite, but with somewhat higher indices. Lavendulan is therefore, probably, the copper analogue of erythrite or simply a cupriferous erythrite. It is so poorly characterized, however, and its homogeneity so uncertain that any definite conclusion as to its relationships is unwarranted. FREIRINITE: A NEW MINERAL SPECIES Wrrrrllr F. Fosnac,l United SlatesNational, Museum The cobalt deposits of San Juan, Chile, have provided a number of specimensof a turquois blue arsenate of copper that have been referred by Goldsmith2 to the mineral lavendulan. Examinatiorr of this mineral and of the lavendulan from Joachimstali has shown that the Chilean mineral is well defined both chemically and physi- cally and entirely distinct from the lavendulan. ft does not cor- respond to any known mineral and the name Jreir,i,ni,te,fuom the locality at which it is found, Department of Freirini, Chile, is proposedfor it. The mineral is found in the Blanca Mine, San Juan, Department of Freirini, Chile. It occurs in a tourmalinized igneous rock as thin, roughly parallel veinlets with scaly, granular or columnar structure. Erythrite is abundantly associatedwith the freirinite in similar veinlets or coatings on cracks. Other associatesare cobaltiferous wad, cuprite and malachite. The original sulphide mineral is cobaltite4but none now remains in the specimenscarrv- ing the freirinite. The freirinite is greenish blue in color (centre blue Ridgeway) with a calamine blue streak. It is made up of fine flakes that give the coarser material a satiny lustre. Under the microscope the mineral is seen to be composed of small plates or columns.
    [Show full text]
  • Structural Refinement of Köttigite–Parasymplesite Solid Solution
    Journal of Mineralogical and Petrological Sciences, Volume 111, page 363–369, 2016 Structural refinement of köttigite–parasymplesite solid solution: Unique cation site occupancy and chemical bonding with water molecules Akira YOSHIASA*, Yumiko MIYANO*, Hiroshi ISOBE*, Kazumasa SUGIYAMA**, Hiroshi ARIMA**, † † Akihiko NAKATSUKA***, Koichi MOMMA and Ritsuro MIYAWAKI *Graduate School of Science and Technology, Kumamoto University, Kumamoto 860–8555, Japan **Institute for materials research, Tohoku University, Sendai 980–8577, Japan ***Graduate School of Science and Engineering, Yamaguchi University, Yamaguchi 755–8611, Japan †Department of Geology and Paleontology, National Museum of Nature and Science, Tsukuba 305–0005, Japan Köttigite and parasymplesite form a solid solution of Zn3−x,Fex(AsO4)2 •8H2O. The compositional variations in the köttigite–parasymplesite solid–solution system were determined by SEM/EDS with specimens from Mitate Mine, Miyazaki, Japan, and Ojuela Mine, Mapimi Durango, Mexico. Variations were observed in the direction perpendicular to the (010) plane in the continuous solid–solution system. A refinement of the crystal structure of Zn1.62Fe1.38(AsO4)2 •8H2O [monoclinic, space group C2/m, a = 10.3417(13), b = 13.4837(16), c = 4.7756(5) Å, β =105. 306(4)°, V = 642.31(13) Å3, and Z = 4] converged into R = 0.0265 and S = 1.083 for 650 independent reflections in the single–crystal XRD data. The hydrogen bonds were described based on the hydrogen atom positions on the difference Fourier maps in reference to the bond valence calculations. The smaller Zn2+ ion prefers the larger M1 site and the larger Fe2+ ion prefers the smaller M2 site. This unique cation site preference reduces the structural distortions.
    [Show full text]
  • Mineralogy of Sediments from Lake Waiau, Hawaii]
    Pacific Science (1978), vol. 32, no. 2 © 1978 by The University Press of Hawaii. All rights reserved Mineralogy of Sediments from Lake Waiau, Hawaii] POW-FOONG FANz ABSTRACT: Fourteen sediment samples from Lake Waiau, a tropical alpine lake in Hawaii, were analyzed by X-ray diffraction for their mineral com­ position. Plagioclase is the major mineral; others are montmorillonite, goethite, and quartz. Plagioclase is derived from local tephra; montmorillonite and goethite are weathering products; and quartz is of eolian origin. A diagenetic mineral, vivianite, is also present. LAKE WAIAU IS LOCATED in Waiau Cone Joint Committee on Powder Diffraction (3980 meters) near the top of Mauna Kea on Standards (JCPDS 1960, Inorganic sets 1-5, Hawaii Island (Figure I). The lake, which p. 558 3-0070). The differences in some of averages 90 meters in diameter with a maxi- the d-spaces of the vivianite from the JCPDS mum depth of less than 3 meters, is an ideal standard may be caused by variations in its natural sediment trap. Woodcock, Rubin, chemical composition. It is nowhere abun­ and Duce (1966) reported 7.5 meters of sedi- dant enough to be detected by whole-rock ments present in the lake, which probably X-ray diffraction analysis. existed in Pleistocene time. Plagioclase is derived locally from tephra. Two cores collected during 1966 have be- Montmorillonite and goethite are weathering come available for analysis of their bulk products of the tephra. Goethite probably mineral composition. The sediments of these formed from the alteration ofolivine, magne­ cores consist of thinly layered, light-brown, tite, and pyroxene that derived from the olive-to-reddish silty clay interbedded with tephra.
    [Show full text]
  • A Blue Encrustation Found on Skeletal Remains of Americans Missing in Action in Vietnam
    Forensic Science International 97 (1998) 79±86 A blue encrustation found on skeletal remains of Americans missing in action in Vietnam Robert W. Manna,* , Melanie E. Feather b , Charles S. Tumosa b , Thomas D. Hollandaa , Kim N. Schneider aPhysical Anthropologists, U.S. Army Central Identi®cation Laboratory, 310 Worchester Ave., Hickam AFB, HI 96853-5530, USA bConservation Scientist and Senior Research Chemist, respectively, Conservation Analytical Laboratory, Smithsonian Institution, CAL-MSC, Washington, DC 20560, USA Received 22 October 1997; received in revised form 5 January 1998; accepted 17 January 1998 Abstract A blue encrustation was found on the repatriated remains of three U.S. Servicemen listed as missing in action (MIA) from Vietnam after 28 years. The identi®cation and origin of the blue material was determined. Scanning electron microscopy with energy dispersive analysis and powder X-ray diffraction identi®ed the material as the mineral vivianite, Fe3422 (PO ) ?8H O. Vivianite has been found often associated with fossilized bone and teeth, but this example is unusual in that it is only the second published forensic example of vivianite growing from human bone after such a short period of time. The presence of vivianite provides information leading to a more complete and accurate understanding of the taphonomic process associated with American MIA remains. 1998 Elsevier Science Ireland Ltd. All rights reserved. Keywords: Vivianite; Bone; Iron II phosphate; Blue encrustation; MIA; Taphonomy 1. Introduction In an effort to resolve the fate of men and women lost during the Vietnam War, the U.S. Army Central Identi®cation Laboratory, Hawaii (CILHI), is responsible for the worldwide search, recovery, and identi®cation of service members and civilians listed as missing in action (MIA).
    [Show full text]
  • Experimental Alteration of Vivianite to Lepidocrocite in a Calcareous Medium
    Clay Minerals (2002) 37, 709–718 Dedicated to Prof. Dr U. Schwertmann on the occasion of his 75th birthday Experimental alteration of vivianite to lepidocrocite in a calcareous medium R. ROLDA´ N, V. BARRO´ N AND J. TORRENT* Departamento de Ciencias y Recursos Agrı´colas y Forestales, Universidad de Co´rdoba, Apdo. 3048, 14080 Co´rdoba, Spain (Received 25 April 2001; revised 28September 2001 ) ABSTRACT: Vivianite [Fe3(PO4)2·8H2O] is easily oxidized in the presence of air. In this work, we studied the oxidation and incongruent dissolution of vivianite in a calcareous medium containing an anion-exchange resin (AER) that acted as a sink for phosphate. Freshly prepared vivianite suspensions with calcite sand and an AER membrane were oxidized and stirred by bubbling air or CO2-free O2. Experiments were finished when oxidation rate and P removal by the AER became slow, which was at 53 days (air system) or 28 days (CO2free O2 system). At these times, the respective values of the Fe(II)/total Fe ratio were 0.29 and 0.12, and the respective values of the atomic P/Fe ratio were 0.15 and 0.11. The final product of the oxidation was poorly crystalline lepidocrocite in the form of thin (1À5 nm), irregular lamellae that were soluble in acid oxalate. The unit-cell edge lengths of this lepidocrocite were a = 0.3117, b = 1.2572, and c = 0.3870, vs. a = 0.3071, b = 1.2520 and c = 0.3873 nm for the reference lepidocrocite. The lepidocrocite lamellae contained occluded P (P/Fe atomic ratio = 0.03À0.04).
    [Show full text]