Gemstones (2009), UnevenArthur Thomas, Gemstones (2009), Brittle, Uneven
Uneven, UnevenAnthony et al, Handbook of mineralogy (2001)
ThCa 2Si 8O 20Walter Schumann , Gemstones of the world (2001) More from other references
Pb 5Cu 2(SO 4) 3(CO 3)(OH) 6Anthony et al , Handbook of mineralogy (2001)