Tenacity
-
-
Solubility
-
-
Durability
-
-
Specific Gravity
3.1-3.23.355-3.433
1
7.18
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Fracture
-
Uneven
Cleavage
Vitreous, pearly on cleavage
{???} Good, {???} Good
Mohs Hardness
3-4-9999
2
10
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Chemical Composition
(Fe2+ ,Mg,Mn2+ ) 3(PO 4) 2 · 4H 2OMichael OâDonoghue , Gems, Sixth Edition (2006) More from other references
(Ca,Mn2+ ,Fe2+ ) 3Al 2BSi 4O 15(OH)Anthony et al , Handbook of mineralogy (2001)