Tolovkite

tolovkite

laurite

pentlandite

heazlewoodite

Images

Formula: IrSbS
Sulphide, cobaltite group, iridium- and antimony- bearing mineral
Crystal system: Isometric
Specific gravity: 10.50 calculated
Hardness: 7½
Streak: Steel-grey
Colour: Grey under reflected light
Magnetism: Not magnetic
Common impurities: Pt,Os,Ni
Environments

Plutonic igneous environments

Localities

At the type locality, the Tolovka River placer, Ust'-Bel'skii ultrabasic Massif, Koryak Okrug, Kamchatka Krai, Russia, tolovkite occurs as intergrowths included in osmium-iridium alloys which come from placer deposits associated with an Alpine-type gabbro massif in the basin of the Tolovka river. The inclusions are anhedral (18 x 18 microns) and also form aggregates with a skeletal isometric crystalline outline (up to 50 x 72 microns). The grains are corroded on the surface and associated with laurite, pentlandite, heazlewoodite and native osmium. Under the binocular, particles of tolovkite have a steel-grey colour, metallic lustre, conchoidal fracture, and are non-magnetic. Under reflected light tolovkite is grey, distinctly paler than laurite but with a very pale brown tint (AM 67.1076-1077, HOM, Mindat).
Tolovkite from the Tolovka River placer - Image

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