UnevenArthur Thomas, Gemstones (2009) Tough, UnevenArthur Thomas, Gemstones (2009) Tough, Brittle, Uneven
Uneven, Subconchoidal, Uneven, Subconchoidal, Splintery, UnevenArthur Thomas, Gemstones (2009)
Mn 8Si 6O 15(OH,Cl) 10Ulrich Henn and Claudio C.
Al 2SiO 5Michael OâDonoghue , Gems, Sixth edition (2006) More from other references