Sengierite Locality: Luiswishi Mine, Lubumbashi (Elizabethville), Katanga Copper Crescent, Katanga (Shaba), Democratic Republic of Congo (Zaïre) Field of view 4 mm. — Photo: Leon Hupperichs · CC BY-SA 3.0
Sengierite
Sengierite is a rare oxide and hydroxide mineral, chemically a copper and uranyl vanadate, belonging to the carnotite group. Its chemical formula is Cu2(OH)2[UO2|VO4]2·6H2O. Sengierite was first discovered at the Luiswishi Mine about 20 kilometres (12 mi) north of Lubumbashi in Katanga Province in the Democratic Republic of the Congo and was first described in 1949 by Johannes F. Vaes and Paul F. Kerr, the mineral was named after Edgar Sengier (1879–1963), a former director of the Union Minière du Haut Katanga.
Intro adapted from Wikipedia (CC BY-SA).
Sengierite is an IMA-recognized mineral species in the vanadate class, with the chemical formula Cu₂(UO₂)₂(VO₄)₂(OH)₂·6H₂O.
It crystallizes in the monoclinic crystal system (space group P2_1/a). It is a member of the Sengierite structural group.
Key properties: Mohs hardness 2.5; specific gravity 4.05; Pale green streak; Vitreous to adamantine luster; optically biaxial.
IMA symbol Sgi, IMA status: approved, named in 1949.
A rare secondary mineral, deposited from solutions derived from primary uraninite.
It is found associated with Volborthite, vandenbrandeite, malachite, chrysocolla, cobalt oxides (Luiswishi mine, Congo); chalcocite, covellite, malachite, tyuyamunite.
The mineral was named to honor Edgard Sengier (1879–1963), Director, Union Minière du Haut Katanga, principal mining company in the former Belgian Congo.