Uneven, Uneven, Gemstones of the world (2001) More from other references
Handbook of mineralogy (2001), Difficult, Fibrous
Ca 10Mg 2Al 4(SiO 4) 5(Si 2O 7) 2(OH) 4Ulrich Henn and Claudio C.
Ca 6Si 6O 17(OH) 2Michael OâDonoghue , Gems, Sixth Edition (2006)