Conchoidal, Uneven, Conchoidal, Brittle, ConchoidalArthur Thomas, Gemstones (2009), Conchoidal to uneven
Uneven, Conchoidal, Gems, Sixth Edition (2006)
[0001] indistinct, [1010] indistinct
Perfect on {001}, less perfect on {010}, intersecting at near 90°; distinct on {110}
Ca 5(PO 4) 3(F,OH,Cl)Walter Schumann , Gemstones of the world (2001) More from other references
(Na,Ca)1-2Si3-2O8