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The Silicate Minerals


Topaz, Al2SiO4(F,OH)2, is the standard mineral for hardness 8 in the Mohs scale of relative hardness. (more below)
Aluminum fluosilicate
Photo (c) 2009 Andrew Alden, licensed to About.com (fair use policy)
Topaz is the hardest silicate mineral, along with beryl. It is usually found in high-temperature tin-bearing veins, in granites, in gas pockets in rhyolite, and in pegmatites. Topaz is tough enough to endure the pounding of streams, where topaz pebbles can occasionally be found.

Its hardness, clarity, and beauty make topaz a popular gemstone, and its well-formed crystals make topaz a favorite of mineral collectors. Most pink topazes, especially in jewelry, are heated to create that color.

Other Primary Minerals
Other Hydrothermal Vein Minerals

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