Topaz
Image: Robert M. Lavinsky (CC BY-SA 3.0)
Mineral NameTopaz
Chemical FormulaAl2SiO4(F,OH)2
Mohs Hardness8
Crystal Systemorthorhombic
Lustervitreous
Streak Colorwhite
Cleavageperfect basal {001}
Fractureconchoidal
Specific Gravity3.49
Colorsbrownish-orange, yellow, blue, pink, colorless, green
Transparencytransparent
Type LocalityTopaz Mountain, Thomas Range, Juab County, Utah, USA
Mineral GroupSilicates
Usesjewelry, collector's specimens
Associated Mineralshematite, quartz, feldspar, fluorite
Rarityuncommon
Description
The image shows a transparent, well-formed, brownish-orange (sherry) topaz crystal with distinct crystal faces, likely terminated, and possibly associated with a dark, metallic mineral.
Geological Context
Topaz typically forms in igneous rocks, especially in granitic pegmatites and rhyolite lava flows, where it crystallizes in cavities or veins. It can also be found in high-temperature hydrothermal veins.
