Tenacity
Solubility
Durability
Specific Gravity
Fracture
Cleavage
Mohs Hardness
Chemical Composition
(Cs,K,Rb)Al 4Be 4(B,Be) 12O 28Anthony et al , Handbook of mineralogy (2001)
Uneven, Conchoidal, ConchoidalWalter Schumann
Indistinct on {001}; partings on {011} and {111}
FeS 2Michael OâDonoghue , Gems, Sixth Edition (2006) More from other references