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Palladosilicide, Pd2Si, a new mineral from the Kapalagulu Intrusion, Western Tanzania and the Bushveld Complex, South Africa

Published online by Cambridge University Press:  02 January 2018

L. J. Cabri ,
A. M. McDonald ,
C. J. Stanley ,
N. S. Rudashevsky ,
G. Poirier ,
H. R. Wilhelmij ,
W. Zhe  and
V. N. Rudashevsky
L. J. Cabri*
Affiliation:
Cabri Consulting Inc., 700-702 Bank Street, PO Box 14087, Ottawa, Ontario, Canada K1S 3V0
A. M. McDonald
Affiliation:
Department of Earth Sciences, Laurentian University, Ramsey Lake Road, Sudbury, Ontario, Canada P3E 2C6
C. J. Stanley
Affiliation:
Natural History Museum, Cromwell Road, London SW7 5BD, UK
N. S. Rudashevsky
Affiliation:
CNT Instruments LTD, Svetlanovsky Ave. 75-41, St. Petersburg, Russia
G. Poirier
Affiliation:
Canadian Museum of Nature, Earth Science Research Services, 1740 Pink Road, Gatineau, Quebec J9J 3N7 (formerly Canmet, Ottawa)
H. R. Wilhelmij
Affiliation:
Ore Deposit Geologist, 3 Norham End, North Oxford OX2 6SG, UK (formerly Lonmin–Goldstream JV, Australia)
W. Zhe
Affiliation:
Central Analytical Facility, Laurentian University, Ramsey Lake Road, Sudbury, Ontario, Canada P3E 2C6
V. N. Rudashevsky
Affiliation:
CNT Instruments LTD, Svetlanovsky Ave. 75-41, St. Petersburg, Russia
*
*E-mail: lcabri@sympatico.ca
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Abstract

Palladosilicide, Pd2Si, is a new mineral (IMA 2014-080) discovered in chromite-rich samples from the Kapalagulu intrusion, western Tanzania (30°03′51′′E 5°53′16′′S and 30°05′37′′E 5°54′26′′S) and from the UG-2 chromitite, Bushveld complex, South Africa. A total of 13 grains of palladosilicide, ranging in size from 0.7 to 39.1 μm (equivalent circle diameters), were found. Synthetic Pd2Si is hexagonal, space group P62m, with a = 6.496(5), c = 3.433(4) Å, V = 125.5(1) Å3, c:a = 0.529 with Z = 3. The strongest lines calculated from the powder pattern (Anderko and Schubert, 1953) are [d in Å (I) (hkl)] 2.3658 100 (111); 2.1263 37 (120); 2.1808 34 (021); 3.240 20 (110); 1.8752 19 (030); 1.7265 12 (002); 1.3403 11 (122); 1.2089 10 (231). The calculated density for three analyses varies from 9.562 to 9.753 g cm–3. Palladosilicide is considered to be equivalent to synthetic Pd2Si based on results from electron backscattered diffraction analyses. Reflectance data in air for the four Commission on Ore Mineralogy wavelengths are [λ nm, R1 (%) R2 (%)] 470 49.6 52.7; 546 51.2 53.8; 589 51.6 53.7; 650 51.7 53.3 and the mineral is bright creamy white against chromite, weakly bireflectant and displays no discernible pleochroism or twinning. It is weakly anisotropic, has weak extinction and rotation tints in shades of blue and olive green. Electron probe microanalyses of palladosilicide yield a simplified formula of Pd2Si.

Keywords

new mineralpalladosilicidesilicideplatinum-group mineralsplatinum-group elementsKapalagulu intrusionTanzaniaUG-2Bushveld ComplexSouth Africapalladium-silicon binary
Type
Research Article
Information
Mineralogical Magazine , Volume 79 , Issue 2 , April 2015 , pp. 295 - 307
Copyright
Copyright © The Mineralogical Society of Great Britain and Ireland 2015

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