Irregular/uneven, ConchoidalArthur Thomas, Gemstones (2009), Conchoidal, Brittle
Uneven, Uneven, ConchoidalAnthony et al, Handbook of mineralogy (2001), Conchoidal, Uneven
Na 2Ca 2Al 6Si 6O 24(CO 3) 2Walter Schumann , Gemstones of the world (2001) More from other references
Mn 3B 7O 13ClMichael OâDonoghue , Gems, Sixth Edition (2006)