Uneven, Uneven, Gemstones of the world (2001) More from other references
Conchoidal, ConchoidalArthur Thomas, Gemstones (2009), Brittle
Ca 10Mg 2Al 4(SiO 4) 5(Si 2O 7) 2(OH) 4Ulrich Henn and Claudio C.
KAlSi 2O 6Michael OâDonoghue , Gems, Sixth Edition (2006) More from other references