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www.mineralgallery.co.za Minerals P-T |
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Topaz |
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Name
Topaz
Chemistry
Al 2 SiO 4 (F, OH) 3, Aluminum silicate fluoride hydroxide
Uses
As a specimen and as a gemstone
Color
Blue yellow, green, white
Hardness
8
Specific gravity
3.4-3.6
Crystals
Orthorhombic
Accompanied by:
Apatite, Beryl, Cassiterite, Fluorite, Tourmaline
Fracture
Subconchoidal to uneven
Luster
Vitreous
Cleavage
Basal perfect.
Streak
White
Similar to:
Quartz
Topaz, an aluminum silicate mineral, is a highly valued gemstone and the birthstone for November.
It forms colorless to straw yellow, bluish or brown, transparent to subtranslucent prismatic crystals (orthorhombic system).
Topaz occurs in high-temperature veins, in pegmatites, and in granites and rhyolites, where it is one of the last minerals to form.
Topaz has a highly perfect cleavage.
Common Topaz is widespread and fine gem material comes from Saxony, the Ural Mountains, Brazil, Japan, Mexico, and Scotland.
