Uneven, Uneven, ConchoidalAnthony et al, Handbook of mineralogy (2001), Brittle, Conchoidal
ConchoidalWalter Schumann, ConchoidalWalter Schumann, Gemstones of the world (2001) More from other references, Splintery
Na(Fe2+3)Al 6(Si 6O 18)(BO 3) 3(OH) 3(OH)Gemdat.org , Management Team (2012)
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