Uneven, UnevenArthur Thomas, Gemstones (2009), Splintery
Subconchoidal, Conchoidal, Brittle, ConchoidalArthur Thomas, Gemstones (2009)
Ca 2(Mg,Fe) 5Si 8O 22(OH) 2Ulrich Henn and Claudio C.
TiO 2Michael OâDonoghue , Gems, Sixth edition (2006) More from other references