Subconchoidal, Conchoidal, Brittle
Conchoidal, Uneven, Conchoidal, Brittle, ConchoidalArthur Thomas, Gemstones (2009), Conchoidal to uneven
Fair on {100}, poor on {001} and {010}
[0001] indistinct, [1010] indistinct
Mg2Al4Si5O18
Ca 5(PO 4) 3(F,OH,Cl)Walter Schumann , Gemstones of the world (2001) More from other references