UnevenArthur Thomas, Gemstones (2009), UnevenArthur Thomas, Gemstones (2009)
Micaceous, Brittle
Ca 2(Mg,Al) 6(Si,Al,B) 6O 20Michael OâDonoghue , Gems, Sixth Edition (2006) More from other references
KAl 2AlSi 3O 10(OH) 2Walter Schumann , Gemstones of the world (2001) More from other references