Tenacity
Solubility
Durability
Specific Gravity
Fracture
Cleavage
Mohs Hardness
Chemical Composition
Al 4(Ta,Nb) 3(O,OH,F) 14Ulrich Henn and Claudio C.
[010] Perfect, [100] Distinct, [011] Distinct
Amethyst, Clear Quartz, Smoky Quartz, Cacoxenite, Rutile, Geothite, Lepidocrocite