Uneven, Uneven, ConchoidalAnthony et al, Handbook of mineralogy (2001), Brittle, Conchoidal
Conchoidal, Conchoidal, Gemstones of the world (2001)
(Ca,Na)(Mg,Fe,Al)Si 2O 6Anthony et al , Handbook of Mineralogy (2001)
SiO 2 · nH 2OWalter Schumann , Gemstones of the world (2001)