Tenacity
Solubility
Durability
Specific Gravity
Fracture
Cleavage
Mohs Hardness
Chemical Composition
Be 3Al 2Si 6O 18Ulrich Henn and Claudio C.
{010} perfect, {110} distinct, {100} in traces
AlO(OH)Walter Schumann , Gemstones of the world (2001) More from other references