Conchoidal, Uneven, Conchoidal, Brittle, ConchoidalArthur Thomas, Gemstones (2009), Conchoidal to uneven
Irregular/uneven, UnevenArthur Thomas, Gemstones (2009)
Ca 5(PO 4) 3(F,OH,Cl)Walter Schumann , Gemstones of the world (2001) More from other references
CaAl 2Si 4O 12 -6H 2OArthur Thomas , Gemstones (2009)