Formula: Pb2Bi2S5
Sulphosalt of lead and bismuth
Specific gravity: 6.86 to 6.99
Hardness: 2½ to 3
Streak: Black
Colour: Grey
Common impurities: Cu,Fe

Metamorphic environments
Hydrothermal environments

Cosalite occurs in hydrothermal deposits formed at medium temperatures and is also found in contact metasomatic replacements, epithermal replacements, and also in pegmatites. Associated minerals include sphalerite, chalcopyrite, pyrite, skutterudite, cobaltite, bornite, enargite, stromeyerite, bismuth, bismuthinite, calcite, tremolite, diopside, epidote and quartz (HOM).


At the Wolfram pipe, Kingsgate, Gough county, New South Wales, Australia, cosalite occurs as a minor phase associated with galena, galenobismutite and native bismuth. Cosalite also carries inclusions of bismuth and bismuthinite. XRD analysis has also identified intergrowths of cosalite with kobellite (AJM 14.1.21).

At the Cariboo Gold Quartz Mine, Wells, Cariboo Mining Division, British Columbia, Canada, cosalite is relatively well known in association with gold (R&M 96.3.218).

At Lauriéras, Saint-Yrieix-la-Perche, Limoges, Haute-Vienne, Nouvelle-Aquitaine, France, cosalite occurs with gold and arsenopyrite (R&M 96.3.218).

At the Trepča Stari Trg mine, Trepča complex, Trepča valley, Mitrovica, Mitrovica District, Kosovo, lustrous steel-grey to lead-grey acicular cosalite crystals up to 2 cm long were found in a void in a mass of pyrrhotite, pyrite and marcasite, coated by calcite and galena (Minrec 38.4.281-283).

The type locality is the Cosalá mine, Cosalá, Cosalá Municipality, Sinaloa, Mexico.

At the Bessie G mine, La Plata Mining District, La Plata county, Colorado, USA, cosalite occurs with tellurides (R&M 96.3.218).

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