Tenacity
Solubility
Durability
Specific Gravity
Fracture
Cleavage
Mohs Hardness
Chemical Composition
NaCa 2(Mg 4Al)Si 6Al 2O 22(OH) 2Michael OâDonoghue , Gems, Sixth Edition (2006)
{010} perfect, {110} distinct, {100} in traces
AlO(OH)Walter Schumann , Gemstones of the world (2001) More from other references