Gemstones (2009), Flexible Flexible fragments.
Uneven, Uneven, ConchoidalAnthony et al, Handbook of mineralogy (2001)
Al 2Si 4O 10(OH) 2Michael OâDonoghue , Gems, Sixth Edition (2006) More from other references
Ca 5(PO 4) 3FAnthony et al , Handbook of mineralogy (2001)