Tenacity
Brittle
-
Solubility
Gelatinises in acids
-
Durability
-
-
Specific Gravity
2.4-2.52.9-3.5
1
7.18
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Fracture
Uneven, Conchoidal
Conchoidal
Cleavage
Distinct on {110}
{110} Perfect, {???} Distinct, {???} Distinct
Mohs Hardness
5-65.5-6
2
10
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Chemical Composition
(Na,Ca)4-8Al6Si6(O,S)24(SO4,Cl)1-2
(Mg,Fe2+ ) 2(Mg,Fe2+ ) 5Si 8O 22(OH) 2Anthony et al , Handbook of mineralogy (2001)