Conchoidal, Brittle, Conchoidal, UnevenArthur Thomas, Gemstones (2009), Brittle, Conchoidal
Subconchoidal, Uneven, Conchoidal, Uneven
CaSO 4Michael OâDonoghue , Gems, Sixth edition (2006) More from other references
Mn2+ Al(PO 4)(OH) 2H 2OMichael OâDonoghue , Gems, Sixth Edition (2006)