Margaritasite

Margaritasite is a yellow, caesium-bearing mineral in the carnotite group. Its chemical formula is (Cs, K, H3O)2(UO2)2V2O8·H2O and its crystal system is monoclinic (space group P21/a ).

Name and discovery
It was first described in 1982 from the Margaritas uranium deposit in the Peña Blanca district of the municipality of Aldama, in the Mexican state of Chihuahua.