UnevenArthur Thomas, Gemstones (2009), UnevenArthur Thomas, Gemstones (2009)
Conchoidal, ConchoidalAnthony et al, Conchoidal, Brittle, Conchoidal
(Fe,Mn) 7Si 7O 21Ulrich Henn and Claudio C.
(Zn,Cu)Al 6(PO 4) 4(OH) 8 · 4H 2OMichael OâDonoghue , Gems, Sixth Edition (2006)