A single, slender Cosalite crystal.
CHEMISTRY - Pb2Bi2S5
CRYSTALLOGRAPHY - Orthorhombic, prismatic
CRYSTAL GROWTH AND HABITS - Cosalite commonly forms elongated prismatic fibers. It can occur as radiating crystals, fibrous groups or it can be feathery.
COLOR AND OPTICAL PROPERTIES - Cosalite is a lead gray to steel gray color. It is opaque.
HARDNESS - 2.5 - 3
SPECIFIC GRAVITY - 6.8 - 7.1
LUSTER - Metallic
STREAK - Black
BREAKABILITY - Uneven fracture
OCCURRENCE - Cosalite is found in hydrothermal deposits associated with primary sulfide ores of lead and bismuth. It can also be found in contact metasomatic replacements associated with lead and bismuth ores.
ASSOCIATED MINERALS - Pyrite, Sphalerite, Chalcopyrite, Cobaltite, Bornite, Skutterudite, Bismuth, Calcite, Epidote, Quartz
MINERAL NAME - Named after the Cosala Mine near Sinaloa, Mexico.