Conchoidal, Brittle, Conchoidal, UnevenArthur Thomas, Gemstones (2009), Brittle, Conchoidal
Uneven, Uneven, ConchoidalAnthony et al, Handbook of mineralogy (2001)
CaSO 4Michael OâDonoghue , Gems, Sixth edition (2006) More from other references
Ca 5(PO 4) 3FAnthony et al , Handbook of mineralogy (2001)