Uneven, Uneven, ConchoidalArthur Thomas, Gemstones (2009), Conchoidal, Brittle
Gemstones (2009), UnevenArthur Thomas, Gemstones (2009), Brittle, Metallic
(Mg,Fe) 5(SiO 4) 2(F,OH) 2Ulrich Henn and Claudio C.
CuSMichael OâDonoghue , Gems, Sixth edition (2006) More from other references