Conchoidal, Brittle, Conchoidal, UnevenArthur Thomas, Gemstones (2009), Brittle, Conchoidal
Gemstones (2009), UnevenArthur Thomas, Gemstones (2009), Brittle, Uneven
CaSO 4Michael OâDonoghue , Gems, Sixth edition (2006) More from other references
ThCa 2Si 8O 20Walter Schumann , Gemstones of the world (2001) More from other references