Al2SiO4(F,OH)2Orthorhombic
Topaz
Al2SiO4(F,OH)2
SilicatesChemical FormulaAl2SiO4(F,OH)2
Crystal SystemOrthorhombic
Mohs Hardness8
Specific Gravity3.53
ColorColorless, yellow, blue, pink, brown
LusterVitreous
StreakWhite
CleavageOne direction
FractureConchoidal to uneven
Occurrence
Found in igneous rocks, especially granites and rhyolites. Popular gemstone.