Conchoidal, ConchoidalArthur Thomas, Gemstones (2009), ConchoidalArthur Thomas, Gemstones (2009), Brittle, Conchoidal
ConchoidalWalter Schumann, Gemstones of the world (2001), ConchoidalWalter Schumann, Gemstones of the world (2001)
CaCO 3Ulrich Henn and Claudio C.
SiO 2 · nH 2OWalter Schumann , Gemstones of the world (2001)