Tenacity
-
-
Solubility
-
-
Durability
-
-
Specific Gravity
3.76-3.773.1-3.2
1
7.18
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Fracture
-
-
Cleavage
{110} Perfect, {110} Perfect
Vitreous, pearly on cleavage
Mohs Hardness
5-63-4
2
10
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Chemical Composition
(Fe,Mn) 7Si 7O 21Ulrich Henn and Claudio C.
(Fe2+ ,Mg,Mn2+ ) 3(PO 4) 2 · 4H 2OMichael OâDonoghue , Gems, Sixth Edition (2006) More from other references