Tenacity
-
Brittle
Solubility
-
insoluble in water
Durability
-
-
Specific Gravity
3.355-3.4335.00-5.20
1
7.18
👆🏻
Fracture
Uneven
Uneven, Conchoidal, ConchoidalWalter Schumann
Cleavage
{???} Good, {???} Good
Indistinct on {001}; partings on {011} and {111}
Mohs Hardness
-99996-6.5
2
10
👆🏻
Chemical Composition
(Ca,Mn2+ ,Fe2+ ) 3Al 2BSi 4O 15(OH)Anthony et al , Handbook of mineralogy (2001)
FeS 2Michael OâDonoghue , Gems, Sixth Edition (2006) More from other references