Tenacity
Solubility
Durability
Specific Gravity
Fracture
Cleavage
Mohs Hardness
Chemical Composition
Rare tabular and prismatic crystals. Usually occurs as fibrous, parallel veins that break off into cleavage fragments.
CaSO 4Michael OâDonoghue , Gems, Sixth edition (2006) More from other references
Mn 3Al 2(SiO 4) 3Arthur Thomas , Gemstones (2009)