Tenacity
Solubility
Durability
Specific Gravity
Fracture
Cleavage
Mohs Hardness
Chemical Composition
Ca10(Mg,Fe)2(Si2O7)2(SiO4)2O(OH)2
Sub-Conchoidal, Irregular/uneven, Uneven, Conchoidal
[100] Perfect, [110] Good, [011] Distinct
(Li,Na)Al(PO 4)(F,OH)Michael OâDonoghue , Gems, Sixth edition (2006) More from other references