Gemstones (2009), UnevenArthur Thomas, Gemstones (2009), Brittle, Uneven
Not Available
ThCa 2Si 8O 20Walter Schumann , Gemstones of the world (2001) More from other references
NaFe 3+ 3 Al 6 (BO 3 ) 3 Si 6 O 18 (O,F,OH) 4 Anthony et al, Handbook of mineralogy (2001)