THE MINERAL LINNAEITE

Chemistry: Co3S4, Cobalt Sulfide.
Class: Sulfides
Uses: As an important ore of cobalt and as mineral specimens.
Specimens

Linnaeite is not a well known mineral but is still an important ore of the strategically valuable metal cobalt. It commonly forms with other cobalt sulfides but usually as just a trace. In a few areas it has formed in large quantities and has become a valuable ore in mines in Zaire and Zambia.

PHYSICAL CHARACTERISTICS OF LINNAEITE:

Color is gray to white, usually with a tarnish if exposed to weathering.
Luster is metallic.
Transparency crystals are opaque.
Crystal System is isometric.
Crystal Habits include small octahedral crystals, usually well formed, and as granular masses in sulfide rocks.
Cleavage is imperfect.
Fracture is uneven.
Hardness is 4.5 - 5.5
Specific Gravity is approximately 4.8 (average for metallic minerals)
Steak is black.
Other Characteristics: A red to violet tarnish forms on weathered specimens.
Associated Minerals include covellite, chalcocite bornite and chalcopyrite
Notable Occurrences include Katanga, Zaire; Zambia; Maryland and California, USA and Seigen, Germany.
Best Field Indicators are crystal habit, streak, associations, tarnish and color.