Conchoidal, Uneven, ConchoidalArthur Thomas, Gemstones (2009), Brittle
Conchoidal, ConchoidalAnthony et al, Conchoidal, Brittle, Conchoidal
(Cs,Na)(AlSi 2O 6) · 0.5H 2OWalter Schumann , Gemstones of the world (2001) More from other references
(Zn,Cu)Al 6(PO 4) 4(OH) 8 · 4H 2OMichael OâDonoghue , Gems, Sixth Edition (2006)