Tenacity
Solubility
Durability
Specific Gravity
Fracture
Cleavage
Mohs Hardness
Chemical Composition
Na 2(Ti,Fe)Si 4(O,F) 11Ulrich Henn and Claudio C.
Subconchoidal, Conchoidal
(Fe,Mn)Ta 2O 6Walter Schumann , Gemstones of the world (2001) More from other references