Margaritasite
A yellow caesium-bearing member of the carnotite group — a rare uranyl vanadate.
Intro adapted from Wikipedia (CC BY-SA).
Margaritasite is an IMA-recognized mineral species in the vanadate class, with the chemical formula Cs₂(UO₂)₂(VO₄)₂·H₂O.
It crystallizes in the monoclinic crystal system (space group P2_1/a). It is a member of the Sengierite structural group.
Key properties: specific gravity 5.41; optically biaxial.
IMA symbol Mgt, IMA status: approved, named in 1980.
Occurs as pore fillings and phenocryst casts in felsic volcanic tuffs, which have been altered by high-temperature hydrothermal fluids.
It is found associated with Kaolinite, quartz.
The name refers to the Margaritas deposit, Mexico, that produced the first specimens.
Index entry. This entry combines official IMA/RRUFF species data with published physical-property data and a Wikipedia introduction — a full written entry hasn’t been published yet.
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