Handbook of mineralogy (2001)
Conchoidal, Brittle, Conchoidal, Brittle, Conchoidal, ConchoidalArthur Thomas, Gemstones (2009), Brittle, Conchoidal
(Ca,Mn2+ ) 2(SiO 3OH)(OH)Anthony et al , Handbook of Mineralogy (2001)
Fe 3Al 2(SiO 4) 3Arthur Thomas , Gemstones (2009)