Irregular/uneven, UnevenArthur Thomas, Gemstones (2009)
Conchoidal, ConchoidalArthur Thomas, Gemstones (2009), Brittle, Conchoidal
CaAl 2Si 4O 12 -6H 2OArthur Thomas , Gemstones (2009)
Mg 3B 7O 13ClMichael OâDonoghue , Gems, Sixth Edition (2006) More from other references