Conchoidal, Splintery, Fibrous, UnevenArthur Thomas, Gemstones (2009)
Gemstones (2009), UnevenArthur Thomas, Gemstones (2009), Brittle, Uneven
CaSO 4 -2(H 2O)Arthur Thomas , Gemstones (2009)
ThCa 2Si 8O 20Walter Schumann , Gemstones of the world (2001) More from other references