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Formula: CoAs
Arsenide, nickeline group
Specific gravity: 8.17 calculated
Hardness: 6 to 6½
Colour: Pink
Environments
Langisite occurs in pockets of ore minerals, and in breccia cemented with
calcite and quartz. Associated minerals include
cobaltpentlandite, siegenite,
parkerite, pyrite variety bravoite,
safflorite, maucherite,
pyrite and marcasite
(HOM).
Localities
At the type locality, the Langis mine, Casey Township, Cobalt Area, Cobalt-Gowganda region, Timiskaming District, Ontario, Canada, an unusual
assemblage of arsenides, sulphides and native bismuth has
been found in an ore-bearing fault vein. The arsenides are
safflorite, langisite and maucherite. The
sulphides consist of two distinct sub-assemblages, one of pyrite and
marcasite intimately intergrown, and the other of
bismuthinite, parkerite,
cobaltpentlandite, siegenite,
pyrite variety bravoite and late pyrite. The sequence of deposition was
firstly arsenides, then
pyrite-marcasite, native
bismuth, and finally other sulphides.
The langisite was found only as irregular grains and lamellae in safflorite. It is
generally present near the sulphides, but most of it is separated from the sulphides by safflorite
(CM 9.597-616).
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