UnevenArthur Thomas, Gemstones (2009), UnevenArthur Thomas, Gemstones (2009)
Sub-Conchoidal, ConchoidalArthur Thomas, Gemstones (2009), Brittle
(Fe2+ ,Mg,Mn2+ ) 3(PO 4) 2 · 4H 2OMichael OâDonoghue , Gems, Sixth Edition (2006) More from other references
Cu2H2Si2O5(OH)4