Conchoidal, ConchoidalAnthony et al, Handbook of mineralogy (2001), Brittle
ConchoidalArthur Thomas, Gemstones (2009), ConchoidalArthur Thomas, Gemstones (2009), Brittle, Conchoidal
MgF 2Ulrich Henn and Claudio C.
ZrO 2Arthur Thomas , Gemstones (2009)