ConchoidalArthur Thomas, Gemstones (2009), ConchoidalArthur Thomas, Gemstones (2009), Brittle, Conchoidal
UnevenWalter Schumann, Gemstones of the world (2001) More from other references, UnevenWalter Schumann, Gemstones of the world (2001) More from other references, Uneven
ZrO 2Arthur Thomas , Gemstones (2009)
(Zn,Fe)SMichael OâDonoghue , Gems, Sixth Edition (2006) More from other references