Tenacity
-
-
Solubility
-
insoluble
Durability
-
-
Specific Gravity
3.355-3.4332.36
1
7.18
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Fracture
Uneven
Uneven, Subconchoidal, Fibrous
Cleavage
{???} Good, {???} Good
[110] perfect, [101] good, [010] distinct
Mohs Hardness
-99993.5-4
2
10
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Chemical Composition
(Ca,Mn2+ ,Fe2+ ) 3Al 2BSi 4O 15(OH)Anthony et al , Handbook of mineralogy (2001)
Al 3(PO 4) 2(OH,F) 3 · 5H 2OMichael OâDonoghue , Gems, Sixth Edition (2006) More from other references