Skutterudite is a
cobalt arsenide mineral that has variable amounts of
nickel and
iron substituting for cobalt with a general formula: (Co,Ni,Fe)As
3. Some references give the arsenic a variable formula subscript of 2-3. High nickel varieties are referred to as nickel-skutterudite, previously chloanthite. It is a
hydrothermal ore mineral found in moderate to high temperature veins with other Ni-Co minerals. Associated minerals are
arsenopyrite, native
silver,
erythrite,
annabergite,
nickeline,
cobaltite, silver
sulfosalts, native
bismuth,
calcite,
siderite,
barite and
quartz. It is mined as an ore of cobalt and nickel with a by-product of
arsenic.