Bornite

A large, anhedral mass of mixed sulfides, dominated by blue (tarnished) bornite and brown, nonfluorescent sphalerite, in contact with a calcite-rich matrix rock containing grains of fluorescent sphalerite (fluorescent orange, pink, and blue LW), bornite, franklinite, and traces of chalcopyrite or pyrite. The presence of both nonfluorescent, somewhat ferroan sphalerite and fluorescent, nearly iron-free sphalerite in different parts of the same specimen is intriguing. The sulfide mass contains numerous small bits of calcite, many 3-6 mm long and crudely oriented in parallel. This is specimen FMM-2761 of the Franklin Mineral Museum and was purchased from collector Doug Wahl in September 2021.

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