What question did this study set out to answer?

The study investigates the formation of hollingworthite and sperrylite intergrowths in copper-nickel sulfide ores.

April 3, 2026

Sperrylite and Hollingworthite Intergrowths in Cu–Ni Sulfide Ores of the Baikal and Norilsk Deposits

Key Points

The study investigates the formation of hollingworthite and sperrylite intergrowths in copper-nickel sulfide ores.
Analyzed primary Cu–Ni sulfide ores from the Norilsk and Baikal deposits.
Examined the composition of sperrylite and hollingworthite metacrystals.
Investigated the interaction of As- and Pt-rich fluids with pyrrhotite.
Identified significant amounts of sperrylite and hollingworthite in the Norilsk and Baikal deposits.
Found that pyrrhotite contains up to 31 ppm Rh, along with Ru and Ir.
Characterized the chemical composition of sperrylite and hollingworthite metacrystals, noting variations between deposits.

Abstract

This paper considers the issue of the formation of hollingworthite (RhAsS)–sperrylite (PtAs2) intergrowths. Primary (nonmetamorphosed) Cu–Ni sulfide pentlandite–pyrrhotite ores contain intergrowths of sperrylite and hollingworthite metacrystals in the Norilsk and Baikal deposits. Pyrrhotite of these ores contains up to 31 ppm Rh and a noticeable amount of Ru and Ir; the mineral formed during subsolidus transformation of the high-temperature sulfide solid solution Mss (an early crystallization product of sulfide Fe–Cu–Ni melt). The Norilsk ores host a significant amount of metacrystals of sperrylite, which is the latest among the pneumatolytic (fluid–metasomatic) Pd, Pt, Au, and Ag minerals. The composition of the Norilsk sperrylite is typically close to PtAs2. The sperrylite metacrystals contain up to 11 wt % Sb in areas with geversite PtSb2, stibiopalladinite Pd5Sb2 or naldrettite Pd2Sb. The low-sulfide ores of the ultramafic–mafic Yoko-Dovyren pluton (Baikalides of the Northern Baikal region) contain no sperrylite. Single sperrylite metacrystals occur only at the contact of the pluton with hornfelized pyrite-bearing black shales. Abundant sperrylite occurs in Cu–Ni sulfide ores of the Baikal deposit, which is hosted in the lower exo- and endocontact of the Yoko-Dovyren pluton at the boundary with hornfelized pyrite-bearing black shales. Sperrylite in the pyrrhotite ores of the Norilsk and Baikal deposits is an interaction product of As- and Pt-rich fluids and pyrrhotite. It is evident that these fluids extracted Rh (as well as Ru and Ir) from pyrrhotite solid solution to form sperrylite and hollingworthite intergrowths. The composition of sperrylite from these intergrowths is (Pt0.985Rh0.015)1(As1.965Se0.035)2 (Norilsk) and (Pt0.985Rh0.015)1(As1.935Sb0.065)2 (Baikal). The Norilsk hollingworthite is enriched in Pt: (Rh0.63Pt0.22Ru0.10Ir0.04)0.99As1.01S0.99Se0.01. In the Baikal hollingworthite, the octahedral crystal growth sector contains Pt (Rh0.84Pt0.05Ir0.02Co0.04Ni0.03Fe0.02)1.00As0.99S1.00Se0.01 at contrast to tetrahedral growth sector without Pt (Rh0.85Ir0.01Co0.08Ni0.04Fe0.02)1.00As0.98S1.00Se0.02.

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Cite This Study

E. M. Spiridonov (Mon,) studied this question.

synapsesocial.com/papers/69cf5de95a333a821460bf4e https://doi.org/https://doi.org/10.3103/s0145875225700929

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