Fourmarierite , Becquerelite , Uraninite Locality: Shinkolobwe Mine (Kasolo Mine), Shinkolobwe , Central area, Katanga Copper Crescent, Katanga (Shaba) , Democratic Republic of Congo (Zaïre) ( Locality at mindat.org ) Size: 5 x 5 x 4 cm. A rich example of Uraninite covered with red hexagonal Fourmarierite crystals. The crystals are associated with good sized and well formed Becquerelite crystals. Shinkolobwe is the type locality for both of Fourmarierite and Becquerelite. Ex. Carnegie Museum Collection. — Photo: Robert M. Lavinsky · CC BY-SA 3.0
Fourmarierite
A secondary lead-uranyl oxide named for Belgian geologist Paul Fourmarier.
Intro adapted from Wikipedia (CC BY-SA).
Fourmarierite is an IMA-recognized mineral species in the oxides & hydroxide class, with the chemical formula Pb₁₋ₓO₃₋₂ₓ(UO₂)₄(OH)₄₊₂ₓ·4H₂O.
It crystallizes in the orthorhombic crystal system (space group Bb2_1m). It is a member of the Schoepite structural group.
Key properties: Mohs hardness 3–4; specific gravity 6.05; Adamantine to subadamantine luster; optically biaxial.
IMA symbol Fmr, grandfathered status — known before the IMA’s founding, named in 1924.
A rare secondary mineral formed as an alteration product of uraninite in the oxide zone of uranium deposits; a common component of “gummite” replacing uraninite; may replace fossil wood.
It is found associated with Uraninite, ianthinite, schoepite, becquerelite, billietite, dewindtite, phosphuranylite, vandendriesscheite, rutherfordine, torbernite, kasolite, curite.
The mineral was named to honor Paul Fourmarier (1877–1970), Belgian geologist, Professor of Geology, University of Liège, Liège, Belgium.