Tenacity
Solubility
Durability
Specific Gravity
Fracture
Cleavage
Mohs Hardness
Chemical Composition
Sub-Conchoidal, Conchoidal, Uneven
(Fe,Mn)AlPO 4(OH) 2 -H 2OArthur Thomas , Gemstones (2009)
Uneven, ConchoidalWalter Schumann, Conchoidal
CaB 2(SiO 4) 2Michael OâDonoghue , Gems, Sixth Edition (2006) More from other references