Skutterudite is an uncommon cobalt-nickel arsenide mineral ((Co,Ni)As3). Beautifully crystalline specimen occur in mines in central Morocco (see below). Skutterudite has a metallic luster, bright silvery color, black streak, no cleavage, moderate hardness (H = 5.5 to 6), and moderately high density. It can be an important ore mineral of cobalt and nickel, and is typically found in hydrothermal veins.
Skutterudite (above & below; above: 2.0 cm across; below: field of view 4.4 cm across) from central Morocco.
Geology: Co-Ni mineralized veins in a fault system within the Bou Azzer-El Graara Ophiolite. The ophiolite complex is Proterozoic in age, but the skutterudite mineralization postdates the host rocks.
Locality: Tamdrost Mine, Bou Azzer Mining District, 30 km south of Tazenakht, central Anti-Atlas Mountains, central Morocco.
Silver = skutterudite; medium-gray, nonmetallic-lustered patch at lower left in below photo = calcite.