Tenacity
Solubility
Durability
Specific Gravity
Fracture
Cleavage
Mohs Hardness
Chemical Composition
Fair in four directions forming octahedrons
Cu 2OMichael OâDonoghue , Gems, Sixth Edition (2006) More from other references
(Mg,Fe)Al 2O 4Gemdat.org , Management Team (2012)