Conchoidal, Splintery, Fibrous, UnevenArthur Thomas, Gemstones (2009)
UnevenArthur Thomas, Gemstones (2009), UnevenArthur Thomas, Gemstones (2009), Brittle, Conchoidal
CaSO 4 -2(H 2O)Arthur Thomas , Gemstones (2009)
Ca 2B 5SiO 9(OH) 5Michael OâDonoghue , Gems, Sixth Edition (2006) More from other references