Conchoidal, Metallic, UnevenArthur Thomas, Gemstones (2009), Brittle, Conchoidal
Uneven, Subconchoidal, Uneven, Subconchoidal, Splintery, UnevenArthur Thomas, Gemstones (2009)
Fair in four directions forming octahedrons
Good on {110}, poor on {100}
Cu 2OMichael OâDonoghue , Gems, Sixth Edition (2006) More from other references
Al 2SiO 5Michael OâDonoghue , Gems, Sixth edition (2006) More from other references