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^[3]).

Margaritasite
General
Category	Carnotite group
Formula	(Cs, K, H3O)2(UO2)2V2O8·H2O
IMA symbol	Mgt[1]
Strunz classification	7/E.11-60
Dana classification	40.2a.28.2
Crystal system	Monoclinic
Crystal class	2/m – Prismatic
Space group	P21/a (no. 14)
Unit cell	a = 10.514(3) Å, b = 8.425(3) Å, c = 7.252(5) Å β = 106.01°
Identification
Color	Yellow
Crystal habit	Tabular crystals, typically massive
Diaphaneity	Translucent
Specific gravity	5.41
Optical properties	Biaxial (−) α = [< 1.83] (synthetic). β = 2.49(1) γ = > 2.7
2V angle	45.5◦
Other characteristics	Radioactive
References	[2][3][4]

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.

See also

• List of minerals