Conchoidal, Uneven, Conchoidal, Brittle, ConchoidalArthur Thomas, Gemstones (2009), Conchoidal to uneven
Conchoidal, ConchoidalArthur Thomas, Gemstones (2009), Brittle
Ca 5(PO 4) 3(F,OH,Cl)Walter Schumann , Gemstones of the world (2001) More from other references
Mg 3Al 2(SiO 4) 3Arthur Thomas , Gemstones (2009)