Tenacity
-
Brittle
Solubility
-
-
Durability
-
-
Specific Gravity
3.355-3.4332.90-2.98
1
7.18
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Fracture
Uneven
Conchoidal
Cleavage
{???} Good, {???} Good
Rare tabular and prismatic crystals. Usually occurs as fibrous, parallel veins that break off into cleavage fragments.
Mohs Hardness
-99993.5
2
10
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Chemical Composition
(Ca,Mn2+ ,Fe2+ ) 3Al 2BSi 4O 15(OH)Anthony et al , Handbook of mineralogy (2001)
CaSO 4Michael OâDonoghue , Gems, Sixth edition (2006) More from other references