Conchoidal, Conchoidal, Gemstones of the world (2001)
Conchoidal, ConchoidalAnthony et al, Conchoidal, Brittle, Conchoidal
SiO 2 · nH 2OWalter Schumann , Gemstones of the world (2001)
(Zn,Cu)Al 6(PO 4) 4(OH) 8 · 4H 2OMichael OâDonoghue , Gems, Sixth Edition (2006)