Tenacity
Solubility
Durability
Specific Gravity
Fracture
Cleavage
Mohs Hardness
Chemical Composition
None, but may exhibit slight parting
(Mg,Zn)Al 2O 4Gemdat.org , Management Team (2012)
Conchoidal, ConchoidalWalter Schumann
Perfect in three directions
CuSiO 2(OH) 2Michael OâDonoghue , Gems, Sixth Edition (2006) More from other references