Conchoidal, ConchoidalAnthony et al, Handbook of mineralogy (2001), Brittle
ConchoidalWalter Schumann, ConchoidalWalter Schumann, Gemstones of the world (2001) More from other references, Splintery
SiCArthur Thomas , Gemstones (2009)
Na 4Al 3Si 9O 24Cl to Ca 4Al 6Si 6O 24(CO 3,SO 4)Walter Schumann , Gemstones of the world (2001) More from other references