Tenacity
Brittle
-
Solubility
-
-
Durability
-
-
Specific Gravity
2.7-3.33.1-3.2
1
7.18
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Fracture
Uneven, Even
-
Cleavage
Perfect on the {001}
Vitreous, pearly on cleavage
Mohs Hardness
2.5-3.03-4
2
10
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Chemical Composition
K(Mg,Fe++)3[AlSi3O10(OH,F)2
(Fe2+ ,Mg,Mn2+ ) 3(PO 4) 2 · 4H 2OMichael OâDonoghue , Gems, Sixth Edition (2006) More from other references