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Putnisite, SrCa4Cr83+ (CO3)8SO4(OH)16·25H2O, a new mineral from Western Australia: description and crystal structure

Published online by Cambridge University Press:  05 July 2018

P. Elliott ,
G. Giester ,
R. Rowe  and
A. Pring
P. Elliott*
Affiliation:
School of Earth and Environmental Sciences, The University of Adelaide, Adelaide, South Australia 5005, Australia South Australian Museum, North Terrace, Adelaide, South Australia 5000, Australia
G. Giester
Affiliation:
Institut für Mineralogie und Kristallographie, Geozentrum, Universität Wien, Althanstrasse 14, A-1090 Vienna, Austria
R. Rowe
Affiliation:
Research Division, Canadian Museum of Nature, P.O. Box 3443, Station D, Ottawa, Ontario K1P 6P4, Canada
A. Pring
Affiliation:
South Australian Museum, North Terrace, Adelaide, South Australia 5000, Australia
*
*E-mail: [email protected]
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Abstract

Putnisite, SrCa4Cr83+ (CO7)8SO4(OH)16·25H2O, is a new mineral from the Polar Bear peninsula, Southern Lake Cowan, Western Australia, Australia. The mineral forms isolated pseudocubic crystals up to 0.5 mm in size in a matrix composed of quartz and a near amorphous Cr silicate. Putnisite is translucent, with a pink streak and vitreous lustre. It is brittle and shows one excellent and two good cleavages parallel to {100}, {010} and {001}. The fracture is uneven and the Mohs hardness 1½−2. The measured density is 2.20(3) g/cm3 and the calculated density based on the empirical formula is 2.23 g/cm3. Optically, putnisite is biaxial negative, with α = 1.552(3), β = 1.583(3) and γ = 1.599(3) (measured in white light). The optical orientation is uncertain and pleochroism is distinct: X pale bluish grey, Y pale purple, Z pale purple. Putnisite is orthorhombic, space group Pnma, with a = 15.351(3), b = 20.421(4) Å, c = 18.270(4) Å, V = 5727(2) Å3 (single-crystal data), and Z = 4. The strongest five lines in the X-ray powder diffraction pattern are [d(Å)(I)(hkl)]: 13.577 (100) (011), 7.659 (80) (200), 6.667 (43) (211), 5.084 (19) (222, 230), 3.689 (16) (411). Electron microprobe analysis (EMPA) gave (wt.%): Na2O 0.17, MgO 0.08, CaO 10.81, SrO 5.72, BaO 0.12, CuO 0.29, Cr2O3 31.13, SO3 3.95, SiO2 0.08, Cl− 0.28, CO2calc 17.94, H2Ocalc 30.30, O=Cl−0.06, total 100.81. The empirical formula, based on O + Cl = 69, is: Cr8.023+Ca3.78Sr1.08Na0.11Cu0.072+Mg0.04Ba0.02[(SO4)0.96(SiO4)0.03]0.99 (CO3)7.98(OH)16.19Cl0.15·24.84H2O. The crystal structure was determined from single-crystal X-ray diffraction data (MoKα, CCD area detector and refined to R1 = 5.84% for 3181 reflections with F0 > 4σF. Cr(OH)4O2 octahedra link by edge-sharing to form an eight-membered ring. A 10-coordinated Sr2+ cation lies at the centre of each ring. The rings are decorated by CO3 triangles, each of which links by corner-sharing to two Cr(OH)4O2 octahedra. Rings are linked by Ca(H2O)4O4 polyhedra to form a sheet parallel to (100). Adjacent sheets are joined along [100] by corner-sharing SO4 tetrahedra. H2O molecules occupy channels that run along [100] and interstices between slabs. Moderate to weak hydrogen bonding provides additional linkage between slabs.

Keywords

putnisitenew mineral speciescrystal structurestrontium calcium chromium sulfate carbonatePolar Bear peninsulaWestern Australia
Type
Research Article
Information
Mineralogical Magazine , Volume 78 , Issue 1 , February 2014 , pp. 131 - 144
Copyright
Copyright © The Mineralogical Society of Great Britain and Ireland 2014

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References

Baur, W.H. (1972) Prediction of hydrogen bonds and hydrogen atom positions in crystalline solids. Acta Crystallographica, B28, 1456–1465.CrossRefGoogle Scholar
Brown, I.D. (1996) VALENCE: a program for calculating bond-valences. Journal of Applied Crystallography, 29, 479–480.CrossRefGoogle Scholar
Brown, I.D. and Altermatt, D. (1985) Bond-valence parameters obtained from a systematic analysis of the inorganic crystal structure database. Acta Crystallographica, B41, 244–247.CrossRefGoogle Scholar
Hawthorne, F.C., Krivovichev, S.V. and Burns, P.C. (2000) The crystal chemistry of sulfate minerals. Pp. 1–112 in: Sulfate Minerals – Crystallography, Geochemistry, and Environmental Significance, (C.N. Alpers, J.L. Jambor and D.K. Nordstrom editors). Reviews in Mineralogy and Geochemistry, 40, Mineralogical Society of America and Geochemical Society, Washington, D.C. Google Scholar
Laugier, J. and Bochu, B. (2003) CELREF http://www.ccp14.ac.uk/tutorial/lmgp/celref.htmGoogle Scholar
Mandarino, J.A. (1981) The Gladstone-Dale relationship: Part IV: The compatibility concept and its application. The Canadian Mineralogist, 19, 441–450.Google Scholar
Marston, R.J., Groves, D.I., Hudson, D.R., and Ross, J.R. (1981) Nickel sulfide deposits in Western Australia: a review. Economic Geology, 76, 1330–1363.CrossRefGoogle Scholar
McQueen, K.G. (1981) Volcanic-associated nickel deposits from around the Widgiemooltha dome, Western Australia. Economic Geology, 76, 1417–1443.CrossRefGoogle Scholar
Oxford Diffraction (2009) CrysAlis PRO. Oxford Diffraction Ltd, Yarnton, England.Google Scholar
Pouchou, J.L. and Pichoir, F. (1985) “PAP”ϕ((rZ)) procedure for improved quantitative microanalysis. Pp. 104–106 in: Microbeam Analysis (J.T. Armstrong, editor). San Francisco Press, San Francisco, California, USA.Google Scholar
Rowe, R. (2009) New statistical calibration approach for Bruker AXS D8 Discover microdiffractometer with Hi-Star detector using GADDS software. Powder Diffraction, 24, 263–271.CrossRefGoogle Scholar
Shannon, R.D. (1976) Revised effective ionic radii and systematic studies of interatomic distances in halides and chalcogenides. Acta Crystallographica, A32, 751–767.CrossRefGoogle Scholar
Shape Software (1997) ATOMS for Windows and Macintosh V 4.0, Kingsport, Tennessee, USA.Google Scholar
Sheldrick, G.M. (2008) A short history of SHELX. Acta Crystallographica, A64, 112–122.CrossRefGoogle Scholar
Swager, C.P., Witt, W.K., Griffin, A.L., Ahmat, A.L., Hunter, W.M., McGoldrick, P.J. and Wyche, S. (1992) Late Archaean granite-greenstones of the Kalgoorlie terrane, Yilgarn Craton, Western Australia. Pp. 39–49 in: The Archaean: Terrains, Processes and Metallogeny (J.E. Glover and S.E. Ho, editors). University of Western Australia, Publication 22. Nedlands, Western Australia, Australia.Google Scholar
Wilson, A.J.C. (editor) (1992) International Tables for Crystallography, volume C. Kluwer Academic, Dordrecht, The Netherlands, 883 pp.Google Scholar