Irregular, Irregular, Gemstones of the world (2001)
Conchoidal, Brittle, Conchoidal, Brittle, Conchoidal, ConchoidalArthur Thomas, Gemstones (2009), Brittle, Conchoidal
CaCO 3Ulrich Henn and Claudio C.
Fe 3Al 2(SiO 4) 3Arthur Thomas , Gemstones (2009)