UnevenArthur Thomas, Gemstones (2009), UnevenArthur Thomas, Gemstones (2009)
Uneven, Uneven, ConchoidalAnthony et al, Handbook of mineralogy (2001), Conchoidal, Uneven
(Fe,Mn) 7Si 7O 21Ulrich Henn and Claudio C.
Mn 3B 7O 13ClMichael OâDonoghue , Gems, Sixth Edition (2006)