Tenacity
Solubility
Durability
Specific Gravity
Fracture
Cleavage
Mohs Hardness
Chemical Composition
Mn 3Al 2(SiO 4) 3Arthur Thomas , Gemstones (2009)
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