Tenacity
-
-
Solubility
-
-
Durability
-
-
Specific Gravity
2.9-3.55.2
1
7.18
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Fracture
Conchoidal
Subconchoidal, Conchoidal
Cleavage
{110} Perfect, {???} Distinct, {???} Distinct
Good in one direction
Mohs Hardness
5.5-66-6.5
2
10
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Chemical Composition
(Mg,Fe2+ ) 2(Mg,Fe2+ ) 5Si 8O 22(OH) 2Anthony et al , Handbook of mineralogy (2001)
(Fe,Mn)Ta 2O 6Walter Schumann , Gemstones of the world (2001) More from other references