Tenacity
-
-
Solubility
Decomposed by acids
-
Durability
-
-
Specific Gravity
2.965.5
1
7.18
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Fracture
-
Conchoidal
Cleavage
Perfect on {010}
{111} Indistinct, {111} Indistinct, {111} Indistinct
Mohs Hardness
55-5.5
2
10
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Chemical Composition
(K,Na)3Cu20Al3Si29O76(OH)16•~8(H2O)
(Ca,Na) 2Ta 2O 6(O,OH,F)Michael OâDonoghue , Gems, Sixth Edition (2006) More from other references