1 Physical Properties
1.1 Tenacity
1.2 Solubility
Gelatinises in acids
insoluble
1.3 Durability
Not Available
Not Available
1.4 Specific Gravity
1.5 Fracture
Uneven, Conchoidal, Brittle
Subconchoidal, Uneven, ConchoidalArthur Thomas, Gemstones (2009), Irregular
1.6 Cleavage
Distinct on {110}
{100} imperfect, {110} indistinct; partings on {111} or {011}
1.7 Mohs Hardness
1.8 Chemical Composition
(Na,Ca)4-8Al6Si6(O,S)24(SO4,Cl)1-2
SnO 2Michael OâDonoghue , Gems, Sixth Edition (2006) More from other references