Tenacity
Solubility
Durability
Specific Gravity
Fracture
Cleavage
Mohs Hardness
Chemical Composition
SiO 2 · nH 2OGemdat.org , Management Team (2012)
{010} perfect, {110} distinct, {100} in traces
AlO(OH)Walter Schumann , Gemstones of the world (2001) More from other references