Conchoidal, Conchoidal, Gemstones of the world (2001) More from other references, Brittle
Uneven, Uneven, ConchoidalAnthony et al, Handbook of mineralogy (2001), Brittle, Conchoidal
SiO2 · nH2O
(Ca,Na)(Mg,Fe,Al)Si 2O 6Anthony et al , Handbook of Mineralogy (2001)