UnevenArthur Thomas, Gemstones (2009), UnevenArthur Thomas, Gemstones (2009)
UnevenAnthony et al, Handbook of mineralogy (2001), UnevenAnthony et al, Handbook of mineralogy (2001), Brittle, Conchoidal
(Fe,Mn) 7Si 7O 21Ulrich Henn and Claudio C.
CaMoO 4Michael OâDonoghue , Gems, Sixth Edition (2006)