Tenacity
Solubility
Durability
Specific Gravity
Fracture
Cleavage
Mohs Hardness
Chemical Composition
Uneven, Subconchoidal, Splintery
Good on {110}, poor on {100}
Al 2SiO 5Michael OâDonoghue , Gems, Sixth edition (2006) More from other references
Perfect in one direction, indistinct in one direction
K2Na(Ca,Mn)2Ti[O|Si7O18(OH)]