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Formula: Cu2RhIrSb2
Antimonide containing rhodium and
iridium
Crystal System: Isometric
Specific gravity: 10.83 calculated
Colour: Light grey
Environments
Fleetite seems to be the first mineral with rhodium Rh and
iridium Ir positioned in separate structural sites
rather than substituting for each other at a single site (Mindat). It is a relatively new mineral, approved in
2018 and to date (January 2023) reported only from the type locality.
Localities
At the type locality, the Miass River, Chelyabinsk Oblast, Russia, fleetite, a new species of
platinum-group mineral, was discovered intergrown with an
osmium–iridium–ruthenium
alloy in a placer. A single grain 50 μm across was found. Osmium,
ruthenium and iridium are the main
associated minerals; also present are
platinum-iron alloys,
laurite, antimony-rich
irarsite, rhodium-rich
tolovkite, kashinite,
anduoite,
ferronickelplatinum,
heazlewoodite,
platinum-group-element bearing
pentlandite, and digenite, as
well as micrometric inclusions of forsterite,
chromite–magnesiochromite
and magnesium-rich edenite.
Fleetite and other late exotic phases were formed by reaction of the associated alloy phases with a fluid phase
enriched in antimony, arsenic and
sulphur in circulation in the cooling
ophiolite source-rock
(CM 59.2.423–430).
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