Topaz | Define Topaz at Dictionary.com

(tō'pāz') A colorless, blue, yellow, brown, or pink orthorhombic mineral valued as a gem. Topaz occurs as transparent or translucent prisms in silica-rich igneous rocks, such as pegmatite, and in tin-bearing rock veins. Chemical formula: Al 2 SiO 4 (F,OH)

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