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