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