Irregular/uneven, UnevenArthur Thomas, Gemstones (2009)
Conchoidal, Metallic, UnevenArthur Thomas, Gemstones (2009), Brittle, Conchoidal
CaAl 2Si 4O 12 -6H 2OArthur Thomas , Gemstones (2009)
Cu 2OMichael OâDonoghue , Gems, Sixth Edition (2006) More from other references