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www.mineralgallery.co.za Minerals K-O |
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Lepidolite |
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Name
Lepidolite
Chemistry
K(Li,Al)3(Si,Al)4O10(OH,F)2
Uses
Lepidolite is used as a minor jewelry stone and as ornament carving material. It is also used in the industrial field in the manufacture of tough glass and porcelains.
Color
Purple to reddish purple
Hardness
2.5-3
Specific gravity
2.3
Crystals
Usually as small disseminated flakes
Accompanied by:
Quartz, calcite, granite, tourmaline and spodumene
Fracture
It cleaves perfect basal in one direction
Luster
Vitreous;pearly on cleavage surfaces
Cleavage
Basal, perfect
Streak
White
Similar to:
Other micas and vermiculite
Lepidolite is an opaque stone, that has small flakes of mica visible in the purple stone. Lepidolite is a mineral of the lithium group and not a true gemstone. Lepidolite is the lightest known solid. It is usually found in pegmatites.
Some interesting facts about mica is: Mica is a generic name for a group of complex hydrous potassium-aluminum silicate minerals that differ somewhat in chemical composition; examples are biotite, lepidolite, muscovite, phlogopite, and vermiculite. Mica has a low coefficient of expansion, high dielectric strength, good electrical resistivity, a uniform dielectric constant, and capacitance stability; at one time it was the best electrical and thermal insulator known.
The iron content determines the color. Muscovite is generally gray, green, or brown; biotite, brown or black; lepidolite, pink or green; phlogopite, light brown to yellow; and vermiculite, brown. Muscovite has the greatest commercial value and is the mica that is ground and pulverized into pigment grades. Muscovite crystals develop in book-like form with a well-developed basal cleavage that allows splitting the large books into extremely thin sheets or grinding the flakes into thin leaves to produce dry ground mica. These leaves have a diameter-to-thickness ratio of more than 25 to 1Ña ratio higher than that of any other flaky mineral.
