Holmquistite

Description

Holmquistite defines a series of orthorhombic Group 1 amphiboles whose compositions can be expressed as AQBLi2 C[(Mg,Fe2+)3(Al, Fe3+)2] TSi8O22(OH)2. Holmquistites are rather rare amphiboles, and generally occur at the contact between lithium-rich pegmatites and country rocks; their formation has always been ascribed to metasomatism around highly fractionated lithium-rich pegmatites that intrude amphibolites.

This rare mineral comes from Western Australia.

Group: Lithium Amphibole
Crystal System: Orthorhombic
Composition: FeS2
Colour: Black, dark violet, sky blue
Streak: White with blue tinge
Hardness: 5 1/2
Cleavage: none
Fracture: 
Lustre: Vitreous
Specific Gravity: