UnevenArthur Thomas, Gemstones (2009), UnevenArthur Thomas, Gemstones (2009)
Conchoidal, Brittle, Conchoidal, Brittle, Conchoidal, ConchoidalArthur Thomas, Gemstones (2009), Brittle, Conchoidal
{110} Perfect, {110} Perfect
[001] good, [210] distinct
(Fe,Mn) 7Si 7O 21Ulrich Henn and Claudio C.
PbSO 4Michael OâDonoghue , Gems, Sixth edition (2006) More from other references