Sub-Conchoidal, ConchoidalArthur Thomas, Gemstones (2009), Brittle
UnevenWalter Schumann, Gemstones of the world (2001) More from other references, UnevenWalter Schumann, Gemstones of the world (2001) More from other references, Uneven
Cu2H2Si2O5(OH)4
(Zn,Fe)SMichael OâDonoghue , Gems, Sixth Edition (2006) More from other references