Topaz
“Harder than steel”
Mineral
Topaz is a silicate mineral that forms in the cavities of igneous rocks, particularly granites and pegmatites. While often associated with its blue gemstone form, natural topaz is usually colorless or pale yellow — most blue topaz is heat-treated.
Composition
aluminum fluorosilicate (Al₂SiO₄(F,OH)₂)
Where Found
Minas Gerais (Brazil), Ural Mountains (Russia), Thomas Range (Utah, USA), Pakistan
Mohs Hardness
8
Fun Fact
The largest faceted gemstone ever cut is the El-Dorado Topaz from Brazil, weighing an astonishing 31,000 carats (about 6.2 kilograms).
Test Your Knowledge
What distinguishes 'imperial topaz' — the most prized variety — from common topaz?
Related Specimens
Want to identify rocks yourself?