Handbook of mineralogy (2001), Difficult, Fibrous
Uneven, ConchoidalArthur Thomas, Gemstones (2009), Brittle, Metallic
Ca 6Si 6O 17(OH) 2Michael OâDonoghue , Gems, Sixth Edition (2006)
Mg 2Si 2O 6Michael OâDonoghue , Gems, Sixth Edition (2006) More from other references