Tenacity
Solubility
Durability
Specific Gravity
Fracture
Cleavage
Mohs Hardness
Chemical Composition
{001} Perfect, {110} Distinct, {101} Distinct
Be 4Si 2O 7(OH) 2Anthony et al , Handbook of mineralogy (2001)
(Fe,Mg) 3Al 2(SiO 4) 3gemdat.org , Management Team (2012)