Conchoidal, Brittle, Conchoidal, Brittle, Conchoidal, ConchoidalArthur Thomas, Gemstones (2009), Brittle, Conchoidal
Conchoidal, ConchoidalArthur Thomas, Gemstones (2009), Brittle
Fe 3Al 2(SiO 4) 3Arthur Thomas , Gemstones (2009)
(Zn,Mn2+ )OMichael OâDonoghue , Gems, Sixth Edition (2006)