Tenacity
-
Brittle
Solubility
-
-
Durability
-
-
Specific Gravity
3.26-3.362.33-2.37
1
7.18
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Fracture
Conchoidal
ConchoidalWalter Schumann
Cleavage
Good on {100}
Perfect on {010}, good on {100}
Mohs Hardness
6.5-77.5
2
10
👆🏻
Chemical Composition
(Ca,Fe,Mn,Mg) 3Al 2BSi 4O 15(OH)Walter Schumann , Gemstones of the world (2001) More from other references
Be 2BO 3(OH)Ulrich Henn and Claudio C.