Tenacity
Solubility
Durability
Specific Gravity
Fracture
Cleavage
Mohs Hardness
Chemical Composition
{110} Perfect, {110} Perfect
(Fe,Mn) 7Si 7O 21Ulrich Henn and Claudio C.
Subconchoidal, Uneven, Conchoidal
(Mg,Fe2+ ) 9(SiO 4) 4(F,OH)) 2Michael OâDonoghue , Gems, Sixth Edition (2006) More from other references