SENGIERITE

    Class : Phosphates, arsenates, vanadates
    Subclass : Uranyl vanadates
    Crystal system : Monoclinic
    Chemistry : Cu2(UO2)2(VO4)2(OH)2 6H2O
    Rarity : Very rare

Sengierite is a very rare hydrated vanadate of uranium and copper, it is one of these many secondary uranium minerals, first discovered in the deposits of Katanga, then sporadically in Morocco, Argentina and the United States. It is often associated with secondary copper minerals (malachite, chrysocolla) and uranium. It was named in honor of Edgard Sengier, Director of the Union Minière du Haut-Katanga (Democratic Republic of Congo). Sengierite occurs in coatings of hexagonal or square lamellae, flattened according to {001}, of yellowish green color, reaching 2 mm.

Main photo : Sengierite from Luiswishi Mine, Kawama, Katanga, Democratic Republic of Congo © Stephan Wolfsried

Sengierite in the World

The best specimens of sengierite come from Congolese Katanga and Kolwezi, notably from the mines of Luiswishi, Shinkolobwe and Musonoï. Sengierite produces efflorescent masses of 2 cm in diameter laid on chalcocite at Bisbee (Arizona). It is also known at Jáchymov (Czech Republic), at Huemul Mine (Argentina), at the Clara mine (Germany), at Argana-Bigoudine (Morocco), at Valle Benedetta (Italy) and at the Eureka mine (Spain).

Right photo : Sengierite from Luiswishi Mine, Kawama, Katanga, Democratic Republic of Congo © Jason B. Smith

Sengierite in France

In France, sengierite is known at Rabejac, near Lodève (Hérault).

Twinning

No known twinning for this mineral species.

Fakes and treatments

No fakes listed for this mineral species.


Hardness : 2.5
Density : 4.05
Fracture : Undetermined
Streak : Light green

TP : Transparent
RI : 1.760 to 1.970
Birefringence : 0.180 to 0.200
Optical character : Biaxial -
Pleochroism : Visible
Fluorescence : None

Solubility : Acids

Magnetism : NoneRadioactivity : Strong