Tenacity
-
Brittle
Solubility
-
-
Durability
-
-
Specific Gravity
3.26-3.365.50-5.90
1
7.18
👆🏻
Fracture
Conchoidal
Conchoidal
Cleavage
Good on {100}
On {10 1 0}, perfect; parting on {000 1 }
Mohs Hardness
6.5-74
2
10
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Chemical Composition
(Ca,Fe,Mn,Mg) 3Al 2BSi 4O 15(OH)Walter Schumann , Gemstones of the world (2001) More from other references
(Zn,Mn2+ )OMichael OâDonoghue , Gems, Sixth Edition (2006)