A completely analyzed nugget by SEM/EDS composed by 4 very rare mineral species of the Platinum Group Minerals: tolovkite, irarsite, kashinite and native iridium. Four Iridium rarities in a single specimen! Ex Vandenbroucke Museum collection from Waregem, Belgium. — Photo: David Hospital · CC BY-SA 4.0
Tolovkite
Tolovkite is an IMA-recognized mineral species in the sulfosalt class, with the chemical formula IrSbS.
It crystallizes in the orthorhombic crystal system (space group Pca2_1). It is a member of the Cobaltite structural group.
Key properties: specific gravity 10.5; Metallic. R: (442) 36.7, (468) 39.0, (484) 39.9, (525) 42.0, (554) 42.5, (586) 42.9, (621) 43.5, (666) 43.8, (699) 44.0 luster.
IMA symbol Tol, IMA status: approved, named in 1980.
Found in a placer derived from an Alpine-type gabbro massif (Tolovka River, Russia).
It is found associated with Os–Ir alloys, laurite, pentlandite, heazlewoodite (Tolovka River, Russia).
The name is taken from the type locality near the Tolovka River, Russia.