Black metallic crystal aggregates of the very rare Co-Ni sulphide mineral willyamite, associated to galena, from the type locality in Broken Hill (ABH Consols Lode, Broken Hill, New South Wales, Australia). — Photo: David Hospital · CC BY-SA 4.0
Willyamite
Willyamite is an IMA-recognized mineral species in the sulfosalt class, with the chemical formula CoSbS.
It crystallizes in the orthorhombic crystal system (space group Pca2_1). It is a member of the Cobaltite structural group.
Key properties: Mohs hardness 5–5.5; specific gravity 6.76; Metallic. R1 –R2: n.d luster.
IMA symbol Wly, IMA status: approved, named in 1893.
Found in calcite–siderite veins.
It is found associated with Dyscrasite, costibite, calcite, siderite.
The name is derived from the locality in Willyama Township, New South Wales, Australia.