Richetite
Richetite is an IMA-recognized mineral species in the oxides & hydroxide class, with the chemical formula (Fe³⁺,Mg)ₓPb²⁺₈.₆(UO₂)₃₆O₃₆(OH)₂₄·41H₂O.
It crystallizes in the triclinic crystal system (space group P1).
Key properties: specific gravity 6.194; Adamantine luster; optically biaxial.
IMA symbol Rht, grandfathered status — known before the IMA’s founding, named in 1947.
A very rare secondary mineral found in the oxidized zone of a hydrothermal uranium deposit (Shinkolobwe, D.R. Congo).
It is found associated with Uraninite, uranophane, becquerelite, masuyite, torbernite, kasolite, rutherfordine, wölsendorfite (Shinkolobwe, D.R. Congo); metazeunerite, nováčekite.
The mineral was named to honor Emile Richet (1884-1939), Belgian geologist, formerly Chief Geologist, Union Minière du Haut-Katanga.