Conchoidal, Uneven, Conchoidal, Brittle, ConchoidalArthur Thomas, Gemstones (2009), Conchoidal to uneven
UnevenArthur Thomas, Gemstones (2009) Tough, UnevenArthur Thomas, Gemstones (2009) Tough, Brittle, Uneven
Ca 5(PO 4) 3(F,OH,Cl)Walter Schumann , Gemstones of the world (2001) More from other references
Mn 8Si 6O 15(OH,Cl) 10Ulrich Henn and Claudio C.