ConchoidalArthur Thomas, Gemstones (2009), ConchoidalArthur Thomas, Gemstones (2009)
Splintery, Granular, Splintery, Granular, Gemstones (2009)
SiO 2 + H 2OUlrich Henn and Claudio C.
Ca 2(Mg,Fe) 5(OH) 2Walter Schumann , Gemstones of the world (2001) More from other references