Category Sorosilicate Strunz classification 9.BD.05 Space group Ccm21 | Formula
(repeating unit) Be4Si2O7(OH)2 Crystal system Orthorhombic | |
 | ||
Crystal class Pyramidal (mm2)
H-M symbol: (mm2) | ||
Bertrandite is a beryllium sorosilicate hydroxide mineral with composition: Be4Si2O7(OH)2. Bertrandite is a colorless to pale yellow orthorhombic mineral with a hardness of 6-7.
It is commonly found in beryllium rich pegmatites and is in part an alteration of beryl. Bertrandite often occurs as a pseudomorphic replacement of beryl. Associated minerals include beryl, phenakite, herderite, tourmaline, muscovite, fluorite and quartz.
It, with beryl, are ores of beryllium.
It was discovered near Nantes, France in 1883 and named after French mineralogist, Emile Bertrand (1844–1909).
References
Bertrandite Wikipedia(Text) CC BY-SA