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Download hereGENERAL DESCRIPTION
Petalite is a lithium aluminosilicate that is formed in the granitic pegmatites. Although it is a rare mineral, it is, sufficiently abundant to be exploited like lithium ore in some localities.
Petalite can usually be found in cleavable masses. The automorphous crystals are rare. Gemmy-, colourless tp white crystals are cut for jewellery.
Petalite is often associated with other minerals containing lithium, spodumene, tourmaline or lepidolite. Petalite is described in the pegmatite of Varutrask on the island of Utö in Sweden (type-locality), in the Taquara mine in Brazil and on the Elba Island in Italy. It was recently discovered in the pegmatite of Paprok, Kamdesh in Afghanistan, with crystals reaching 20 cm.
The type of this species is kept at the Bergwerk Akademie (“School of Mines”) of Freiberg in Germany.
HISTORY : Name inspired from the Greek word "πεταλον" [petalon] that means "leave". Name given in reference to its cleveage
Species first described in 1800 by José Bonifacio de Andrada e Silva (1763-1838), Brazilian politician and geologist
Type-locality : Utö Island, Haninge, Stockholm area, Sweden
ANCIENT NAME : Castor, castorite
CHEMICAL FORMULA : Li Al Si4O10
CRYSTAL SYSTEM : Monoclinic
COLOR : White, gray, pink
DIAPHANIETY : Transparent to translucent
LUSTER : Vitreous
STREAK : White
MORPHOLOGIE : Prismatic crystals, foliated, lamellars, massive
HARDNESS : 6,5
CHEMICAL CLASS: 2,41-2,42
DENSITY : VIII - Silicates
GROUP : Petalite
STRUNZ CLASS BEFORE 2001 : 8/J.03-10
STRUNZ CLASS AFTER 2001 : 9.EF.05
