UnevenArthur Thomas, Gemstones (2009), UnevenArthur Thomas, Gemstones (2009), Conchoidal, Brittle
ConchoidalWalter Schumann, Gemstones of the world (2001), ConchoidalWalter Schumann, Gemstones of the world (2001)
Ca 2Mg 5Si 8O 22(OH) 2Ulrich Henn and Claudio C.
SiO 2Walter Schumann , Gemstones of the world (2001)