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Formula: Ir5Ni10S16
Sulphide of iridium and nickel,
kuvaevite group,
pentlandite supergroup
Crystal system: Trigonal
Specific gravity: 6.37 calculated
Streak: Grey to brownish grey
Environments
Kuvaevite is a new mineral, approved in 2020 and to date (July 2025) reported only from the Sisim Placer
Zone.
Localities
At the type locality, the Sisim Placer Zone, Lysanskiy dunite-peridotite-gabbro complex, Krasnoyarsk Krai, Russia,
kuvaevite forms small grains (up to 20 µm across) in globular inclusions hosted by grains of
osmium - iridium -
ruthenium alloys (up to 0.5 mm) in ore occurrences along the Ko River.
Rhodium-bearing pentlandite or
oberthürite (or both), minerals of the
laurite-erlichmanite series
and platinum - palladium -
iron alloys are the main associated minerals.
Kuvaevite is grey to brownish grey in colour in reflected light. It forms solid-solution series with
torryweiserite, tamuraite
and ferrotorryweiserite.
Kuvaevite and related sulphides significantly vary in composition in the Ko River placer, in the entire
Sisim zone, and in some other ore occurrences worldwide. Associations of
platinum group minerals observed in ore occurrences at the Ko River
and in the Sisim zone seem to be genetically related to bedrock zones of
chromite-bearing ultramafic
rocks (serpentinites). Kuvaevite and other minerals
present in the polymineralic inclusions, hosted by osmium -
iridium - ruthenium alloys,
formed from droplets of residual melt. This melt accumulated the “incompatible” elements, which could not be
incorporated into the structure of the host alloy, including lithophile (readily forming stable chemical bonds with
oxygen) elements, chalcogens (elements in group 16 of the periodic table)
sulphur and
tellurium, semimetals arsenic,
antimony and bismuth, and base
metals iron, nickel and
copper, as well as relatively low-temperature
platinum group species
platinum and palladium and
rhodium
(Russian Geology and Geophysics 63.12.1373–1387).
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