Not Available
UnevenArthur Thomas, Gemstones (2009), UnevenArthur Thomas, Gemstones (2009)
ZrO 2 + CaO or Y 2O 3 or MgOUlrich Henn and Claudio C.
Ca 2(Mg,Al) 6(Si,Al,B) 6O 20Michael OâDonoghue , Gems, Sixth Edition (2006) More from other references