Tenacity
Solubility
Durability
Specific Gravity
Fracture
Cleavage
Mohs Hardness
Chemical Composition
{010} perfect, {110} distinct, {100} in traces
AlO(OH)Walter Schumann , Gemstones of the world (2001) More from other references
Uneven, Irregular, Conchoidal
Na(Mg 3)Al 6(Si 6O 18)(BO 3) 3(OH) 3(OH)Gemdat.org , Management Team (2012)