Unnamed Pt(Cu_(0.67)Sn_(0.33)) from the Bolshoy Khailyk River, Western Sayans, Russia, and a Review of Related Compounds and Solid Solutions

Creators: Barkov, Andrei Y.; Bindi, Luca; Juárez-Arellano, Erick A.; Tamura, Nobumichi; Shvedov, Gennadiy I.; Ma, Chi; Martin, Robert F.

Abstract

We describe a potentially new species of a platinum cupride–stannide mineral (PCSM) of composition Pt(Cu_(0.67)Sn_(0.33)). It occurs in a placer deposit in the River Bolshoy Khailyk, southern Krasnoyarskiy kray, Russia. A synthetic equivalent of PCSM was obtained and characterized. The PCSM occurs as anhedral or subhedral grains up to 15 μm × 30 μm in association with various platinum-group minerals, Rh–Co-rich pentlandite and magnetite, all hosted by a placer grain of Cu–Au–Pt alloy. Synchrotron micro-Laue diffraction studies indicate that the PCSM mineral is tetragonal and belongs to the inferred space-group P4/mmm (#123). Its unit-cell parameters are a = 2.838 (3) Å, c = 3.650 (4) Å, and V = 29.40 (10) Å³, and Z = 1. The c:a ratio calculated from the unit-cell parameters is 1.286. These characteristics are in good agreement with those obtained for specimens of synthetic Pt(Cu_(0.67)Sn_(0.33)). A review on related minerals and unnamed phases is provided to outline compositional variations and extents of solid solutions in the relevant systems PtNi–PtFe–PtCu, PdCu–PdHg–PdAu, PdHg–PtHg, and AuCu–PtCu. The PCSM-bearing mineralization appears to be related genetically with an ophiolitic source-rock of the Aktovrakskiy complex of the western Sayans. The unnamed phase likely crystallized from microvolumes of a highly fractionated melt rich in Cu and Sn.

Additional Information

© 2021 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https://creativecommons.org/licenses/by/4.0/). Received: 11 October 2021; Accepted: 3 November 2021; Published: 8 November 2021. We thank Ritsuro Miyawaki, Chairman, Commission on New Minerals, Nomenclature and Classification (CNMNC), IMA, for generously sharing his ideas on the general principles of nomenclature involving the Pt(Cu_(0.67)Sn_(0.33)) mineral that we have investigated. This research used beamline 12.3.2 at the Advanced Light Source, which is a DOE Office of Science User Facility under contract no. DE-AC02-05CH11231. A.Y.B. acknowledges that this study was also supported in part by the Russian Foundation for Basic Research (project # RFBR 19-05-00181). A support from the Cherepovets State University is gratefully acknowledged (A.Y.B.). We are grateful to B. Winkler and W. Morgenroth for their contributions in characterization of the synthetic equivalent, and to S.A. Silyanov for the reflectance measurements. We thank the Editorial board members and two anonymous referees for their constructive comments. This research received no specific grant. Data Availability Statement: The data are available upon a reasonable request (from A.Y.B.). Author Contributions: The authors wrote the article together. A.Y.B., R.F.M.: data analysis, interpretations, conclusions, writing; L.B.: XRD study, discussions, writing; E.A.J.-A.: synthesis, characterization of synthetic analogue, discussions, writing; N.T.: Synchrotron X-ray micro-Laue diffraction study, writing; C.M.: electron backscatter diffraction (EBSD) study, writing; G.I.S.: regional investigation, sampling, writing. All authors have read and agreed to the published version of the manuscript. The authors declare no conflict of interest.

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