Petalite

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Petalite
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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