Tenacity
-
-
Solubility
-
-
Durability
-
-
Specific Gravity
1.65-1.993.76-3.77
1
7.18
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Fracture
Uneven
-
Cleavage
{010} Perfect, {110} Perfect
{110} Perfect, {110} Perfect
Mohs Hardness
2-2.55-6
2
10
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Chemical Composition
NaCaB 5O 6(OH) 6 · 5H 2OMichael OâDonoghue , Gems, Sixth Edition (2006)
(Fe,Mn) 7Si 7O 21Ulrich Henn and Claudio C.