Tenacity
-
Brittle
Solubility
-
-
Durability
-
-
Specific Gravity
3.1-3.23.7-3.8
1
7.18
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Fracture
-
Subconchoidal, Conchoidal
Cleavage
Vitreous, pearly on cleavage
Distinct on {010}
Mohs Hardness
3-47-7.5
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
(Fe,Mg,Zn) 2Al 9(Si,Al) 4O 22(OH) 2Ulrich Henn and Claudio C.