Irregular/uneven, UnevenArthur Thomas, Gemstones (2009)
Conchoidal, ConchoidalWalter Schumann, Gemstones of the world (2001) More from other references, Conchoidal, Brittle
CaAl 2Si 4O 12 -6H 2OArthur Thomas , Gemstones (2009)
CuSiO 2(OH) 2Michael OâDonoghue , Gems, Sixth Edition (2006) More from other references