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The Ag-Pd-Se system; phase relations involving minerals and potential new minerals

Anna Vymazalova, Dmitriy A. Chareev, Alexandr V. Kristavchuk, Frantisek Laufek and Milan Drabek
The Ag-Pd-Se system; phase relations involving minerals and potential new minerals
The Canadian Mineralogist (February 2014) 52 (1): 77-89

Abstract

The phase equilibria in the system Ag-Pd-Se were studied by the evacuated-silica glass tube method at 350, 430, and 530 degrees C. In the system we synthesized four ternary phases: Ag (sub 2) Pd (sub 3) Se (sub 4) (chrisstanleyite) and the new phases AgPd (sub 3) Se, (Ag,Pd) (sub 22) Se (sub 6) , and Ag (sub 6) Pd (sub 74) Se (sub 20) . The AgPd (sub 3) Se phase forms a Ag (sub 1-) (sub x) Pd (sub 3+) (sub x) Se (x = 0-0.15) solid-solution series. The (Ag,Pd) (sub 22) Se (sub 6) phase forms a (Ag (sub 11+ or -) (sub x) Pd (sub 11+ or -) (sub x) ) (sub 22) Se (sub 6) (0.2 > or = X > or = 3.9) solid-solution series, the solubility of Ag decreasing with increasing temperature. Palladseite (Pd (sub 17) Se (sub 15) ) forms a limited solid solution and dissolves up to 7 wt.% Ag, and the phase Pd (sub 9) Se (sub 2) dissolves up to 3 wt.% Ag. The Ag (sub 2) Pd (sub 3) Se (sub 4) phase, an analogue of the mineral chrisstanleyite, forms stable associations with naumannite (Ag (sub 2) Se) and veerbekite (PdSe (sub 2) ); it also coexists with palladseite (dissolving 7 wt.% Ag). The phase is stable up to 430 degrees C. Phase relations determined the mineral assemblages that can be expected to occur in nature. Ternary AgPd (sub 3) Se and (Ag,Pd) (sub 22) Se (sub 6) phases and the binary PdSe, Pd (sub 7) Se (sub 4) , and Pd (sub 34) Se (sub 11) phases can be expected in associations with the mineral palladseite, among other selenides. Finding these phases in nature is highly probable in telethermal selenide veins and unconformity-related uranium deposits, at conditions of high Se/S fugacity ratio, an oxidizing environment, and Se-rich fluids, forming at low temperatures. The Ag (sub 6) Pd (sub 74) Se (sub 20) phase forms stable associations with AgPd (sub 3) Se and Pd (sub 7) Se (sub 2) . It also coexists with Pd (sub 4) Se and Pd (sub 9) Se (sub 2) . The Ag (sub 6) Pd (sub 74) Se (sub 20) phase is stable above 430 degrees C. Under natural conditions the Ag (sub 6) Pd (sub 74) Se (sub 20) and Pd (sub 9) Se (sub 2) phases can be expected to occur in less traditional environments than are usual for selenides, forming at higher temperatures (above 430 degrees C).


ISSN: 0008-4476
EISSN: 1499-1276
Coden: CAMIA6
Serial Title: The Canadian Mineralogist
Serial Volume: 52
Serial Issue: 1
Title: The Ag-Pd-Se system; phase relations involving minerals and potential new minerals
Affiliation: Czech Geological Survey, Prague, Czech Republic
Pages: 77-89
Published: 201402
Text Language: English
Publisher: Mineralogical Association of Canada, Ottawa, ON, Canada
References: 46
Accession Number: 2014-046923
Categories: Mineralogy of non-silicates
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. 4 tables
Secondary Affiliation: Institute of Experimental Mineralogy, RUS, Russian FederationUniversity of Dubna, RUS, Russian Federation
Country of Publication: Canada
Secondary Affiliation: GeoRef, Copyright 2017, American Geosciences Institute. Abstract, copyright, Mineralogical Association of Canada. Reference includes data from GeoScienceWorld, Alexandria, VA, United States
Update Code: 201427
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