Topaz
Image: Kurr, J. G. (Johann Gottlob), 1798-1870 (Public domain)
Mineral NameTopaz
Chemical FormulaAl₂SiO₄(F,OH)₂
Mohs Hardness8
Crystal Systemorthorhombic
Lustervitreous
Streak ColorWhite
CleavagePerfect basal (one direction)
FractureConchoidal to uneven
Specific Gravity3.49
Colorscolorless, white, yellow, orange, pink, red, purple, blue, green
TransparencyTransparent to translucent
Type LocalityBrazil, Pakistan, Russia, USA, Mexico
Mineral GroupNesosilicates
Usesjewelry, collector specimens, abrasives
Associated Mineralsquartz, feldspar, mica, cassiterite, fluorite, beryl
Rarityuncommon
Description
This illustration depicts various forms of Topaz, including prismatic crystals with distinct terminations and several faceted gemstones. Colors shown range from light yellow and dark yellow to a sea-green hue.
Geological Context
Topaz typically forms in igneous rocks, particularly granitic pegmatites and rhyolites, and in high-temperature hydrothermal veins. It is often found in association with tin deposits.
