Tenacity
-
Brittle
Solubility
-
Soluble
Durability
-
-
Specific Gravity
3.26-3.363.30-3.50
1
7.18
👆🏻
Fracture
Conchoidal
Uneven, ConchoidalWalter Schumann, Conchoidal
Cleavage
Good on {100}
Perfect on {110}, poor on {101}, {001} rare
Mohs Hardness
6.5-75
2
10
👆🏻
Chemical Composition
(Ca,Fe,Mn,Mg) 3Al 2BSi 4O 15(OH)Walter Schumann , Gemstones of the world (2001) More from other references
Zn 4Si 2O 7(OH) 2H 2OMichael OâDonoghue , Gems, Sixth Edition (2006) More from other references