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