Uneven, Uneven, ConchoidalAnthony et al, Handbook of mineralogy (2001), Conchoidal, Brittle
ConchoidalWalter Schumann, Gemstones of the world (2001), ConchoidalWalter Schumann, Gemstones of the world (2001)
Mg 3(SiO 4)(F,OH) 2Anthony et al , Handbook of Mineralogy (2001)
SiO 2(+Al 2O 3)Walter Schumann , Gemstones of the world (2001)