Irregular/uneven, ConchoidalArthur Thomas, Gemstones (2009), Conchoidal, Brittle
Conchoidal, Metallic, UnevenArthur Thomas, Gemstones (2009), Brittle, Conchoidal
Perfect on {10 1 0}, poor on {0001}
Fair in four directions forming octahedrons
Na 2Ca 2Al 6Si 6O 24(CO 3) 2Walter Schumann , Gemstones of the world (2001) More from other references
Cu 2OMichael OâDonoghue , Gems, Sixth Edition (2006) More from other references