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Siegenite from Buick mine, Bixby, Viburnum Trend District, Iron County, Missouri, USA
Category Sulfide mineral
Thiospinel group
Spinel structural group
(repeating unit)
Strunz classification 2.DA.05
Crystal system Cubic
Crystal class Hexoctahedral (m3m)
H-M symbol: (4/m 3 2/m)
Space group Fd3m
Unit cell a = 9.41 Å; Z = 8
Color Light to steel-grey, violet-gray (tarnished)
Crystal habit As octahedral crystals, granular, massive
Twinning On {111}; polysynthetic
Cleavage Imperfect on {001}
Fracture Irregular to uneven, sub-conchoidal
Mohs scale hardness 4.5 - 5.5
Luster Metallic
Streak Grayish black
Diaphaneity Opaque
Specific gravity 4.5 - 4.8
References [1][2][3]

Siegenite is a cobalt nickel sulfide mineral with formula: (Ni,Co)3S4 (a member of the thiospinel group). It occurs as opaque steel gray octahedral crystals associated with other sulfides.

Discovery and occurrence[edit]

It was first described in 1850 for an occurrence in the Stahlberg Mine in Müsen, Siegerland, North Rhine-Westphalia, Germany and named for the locality.[1] It occurs in hydrothermal copper-nickel-iron sulfide bearing veins associated with chalcopyrite, pyrrhotite, galena, sphalerite, pyrite, millerite, gersdorffite and ullmannite.[2]

It occurs in a variety of deposits worldwide, including Brestovsko in the central Bosnian Mountains of Serbia; at Kladno in the Czech Republic; Blackcraig, Kirkcudbrightshire, Scotland. In the United States occurrences include the Mine la Motte of Madison County and the Buick mine, Bixby, Iron County and in the Sweetwater mine of Reynolds County in the Lead Belt of Missouri. In Canada, it is known from the Langis mine, Cobalt-Gowganda area, Ontario. In Africa it occurs at Shinkolobwe, Katanga Province and Kilembe, Uganda. In Japan it is reported from the Kamaishi mine, Iwate Prefecture, and the Yokozuru mine, north Kyushu. It also occurs at Kalgoorlie, Western Australia.[2] It is found at the Browns deposit, Batchelor, Northern Territory, Australia.[1]