UnevenArthur Thomas, Gemstones (2009), UnevenArthur Thomas, Gemstones (2009)
UnevenAnthony et al, Handbook of mineralogy (2001), UnevenAnthony et al, Handbook of mineralogy (2001)
Ca 2Mg 5Si 8O 22(OH) 2Ulrich Henn and Claudio C.
Na(Mn2+ ,Ca) 2Si 3O 8(OH)Michael OâDonoghue , Gems, Sixth Edition (2006)