Universität zu Köln

Helmy, Hassan M. and Bragagni, Alessandro (2017). Platinum-group elements fractionation by selective complexing, the Os, Ir, Ru, Rh-arsenide-sulfide systems above 1020 degrees C. Geochim. Cosmochim. Acta, 216. S. 169 - 184. OXFORD: PERGAMON-ELSEVIER SCIENCE LTD. ISSN 1872-9533

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Abstract

The platinum-group element (PGE) contents in magmatic ores and rocks are normally in the low lg/g (even in the ng/g) level, yet they form discrete platinum-group mineral (PGM) phases. IPGE (Os, Ir, Ru) + Rh form alloys, sulfides, and sulfarsenides while Pt and Pd form arsenides, tellurides, bismuthoids and antimonides. We experimentally investigate the behavior of Os, Ru, Ir and Rh in As-bearing sulfide system between 1300 and 1020 degrees C and show that the prominent mineralogical difference between IPGE (+ Rh) and Pt and Pd reflects different chemical preference in the sulfide melt. At temperatures above 1200 degrees C, Os shows a tendency to form alloys. Ruthenium forms a sulfide (laurite RuS2) while Ir and Rh form sulfarsenides (irarsite IrAsS and hollingworthite RhAsS, respectively). The chemical preference of PGE is selective: IPGE + Rh form metal-metal, metal-S and metal-AsS complexes while Pt and Pd form semimetal complexes. Selective complexing followed by mechanical separation of IPGE (and Rh)-ligand from Pt-and Pd-ligand associations lead to PGE fractionation. (C) 2017 Elsevier Ltd. All rights reserved.

Item Type:	Journal Article
Creators:	Creators Email ORCID ORCID Put Code Helmy, Hassan M. UNSPECIFIED UNSPECIFIED UNSPECIFIED Bragagni, Alessandro UNSPECIFIED UNSPECIFIED UNSPECIFIED
URN:	urn:nbn:de:hbz:38-213738
DOI:	10.1016/j.gca.2017.01.040
Journal or Publication Title:	Geochim. Cosmochim. Acta
Volume:	216
Page Range:	S. 169 - 184
Date:	2017
Publisher:	PERGAMON-ELSEVIER SCIENCE LTD
Place of Publication:	OXFORD
ISSN:	1872-9533
Language:	English
Faculty:	Unspecified
Divisions:	Unspecified
Subjects:	no entry
Uncontrolled Keywords:	Keywords Language NORTHERN BUSHVELD COMPLEX; GROUP MINERALS; EASTERN DESERT; PGE MINERALIZATION; SILICATE MELTS; EXPERIMENTAL CONSTRAINTS; COLLECTION MECHANISMS; STILLWATER COMPLEX; SOLID-SOLUTION; MERENSKY REEF Multiple languages Geochemistry & Geophysics Multiple languages
Refereed:	Yes
URI:	http://kups.ub.uni-koeln.de/id/eprint/21373