Buttgenbachite Field of view: 4 mm Locality: Likasi Mine (TL), Kambove District, Haut-Katanga, Congo — Photo: Henk Smeets – tomeikminerals.com · CC BY 4.0
Buttgenbachite
Buttgenbachite is an IMA-recognized mineral species in the nitrate class, with the chemical formula Cu₃₆(NO₃)₂Cl₈(OH)₆₂·nH₂O.
It crystallizes in the hexagonal crystal system (space group P6_3/mmc). It is a member of the Connellite structural group.
Key properties: Mohs hardness 3; specific gravity 3.36–3.42; Pale greenish blue streak; Vitreous luster; optically uniaxial.
IMA symbol Bba, grandfathered status — known before the IMA’s founding, named in 1925.
A rare secondary mineral found in the oxidized portions of copper deposits; the nitrate may be of biological origin.
It is found associated with Cuprite, likasite, gerhardtite, malachite, brochantite, silver.
The mineral was named to honor Professor Henri Jean François Buttgenbach (1874–1964), Belgian mineralogist, University of Liège, Liège, Belgium, who long studied Congo minerals.