Petalite

petalite

spodumene

montmorillonite

lepidolite

Images

Formula: LiAlSi4O10
Phyllosilicate (sheet silicate), feldspathoid
Specific gravity: 2.3 to 2.5
Hardness: 6 to 6½
Streak: White
Colour: Colourless, white, grey, pink
Solubility: Insoluble in acids
Common impurities: Mg,Fe,Na,Ca,K,H2O
Environments:

Pegmatites

Petalite is found in granite pegmatites and related rocks, associated with spodumene, tourmaline, lepidolite, topaz, microcline, amblygonite, apatite, pollucite, columbite, albite variety cleavelandite and quartz (Dana, DHZ 4 p274).

Alteration

Petalite alters to montmorillonite (Dana).

petalite to spodumene and quartz
LiAlSi4O10 ⇌ LiAlSi2O6 + 2SiO2
(DHZ 4 p274).

Back to Minerals