Tenacity
-
-
Solubility
-
-
Durability
-
-
Specific Gravity
3.355-3.4332.25-2.40
1
7.18
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Fracture
Uneven
-
Cleavage
{???} Good, {???} Good
perfect on {010}; good on {100}
Mohs Hardness
-99995-5.5
2
10
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Chemical Composition
(Ca,Mn2+ ,Fe2+ ) 3Al 2BSi 4O 15(OH)Anthony et al , Handbook of mineralogy (2001)
NaCa 2Al 5Si 5O 20 · 6H 2OMichael OâDonoghue , Gems, Sixth Edition (2006) More from other references