Cobaltite: Gemstones Information
Cobaltite is CoAsS and forms opaque silver to greyish black pseudocubic or pseudopyritohedral crystals of the orthorhombic system with a perfect cleavage in one direction, hardness 5.5, and SG 6.3. The RI will be out of the range of gemmological instruments. Cobaltite occurs in high temperature hydrothermal deposits and in veins in contact metamor phosed rocks. Specimens, which may show a metallic redness, are found at Cobalt, Ontario, Canada, and fine crystals are found at Tunaberg,Sodermanland, Sweden.