Petalite

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Petalite

General
Category Mineral
Chemical formula lithium aluminium tectosilicate mineral LiAlSi4O10
Identification
Color colorless, grey, yellow, yellow grey, to white
Crystal habit tabular prismatic crystals and columnar masses
Crystal system monoclinic 2/m.
Cleavage Perfect in one plane
Fracture Subconchoidal
Mohs Scale hardness 6 - 6.5
Luster Vitreous, pearly on cleavages
Refractive index nα=1.504, nβ=1.510, nγ=1.516
Streak Colorless
Specific gravity 2.4
Fusibility 5
Solubility Insoluble
Other Characteristics Fluorescent

Petalite, also known as Castorite is a lithium aluminium tectosilicate mineral LiAlSi4O10, crystallizing in the monoclinic system. Petalite is a member of the feldspathoid group. It occurs as colorless, grey, yellow, yellow grey, to white tabular crystals and columnar masses. Occurs in lithium-bearing pegmatites with spodumene, lepidolite, and tourmaline. Petalite is an important ore of lithium. The colorless varieties are often used as gemstones.

Discovered in 1800, type locality: Utö Island, Haninge, Stockholm, Sweden. The name is derived from Greek petalon for leaf.

See also: List of minerals

[edit] References

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