ConchoidalWalter Schumann, Gemstones of the world (2001), ConchoidalWalter Schumann, Gemstones of the world (2001)
Uneven, Uneven, ConchoidalAnthony et al, Handbook of mineralogy (2001), Conchoidal, Uneven
Al 2Be 3Si 6O 18Martin H.
Mn 3B 7O 13ClMichael OâDonoghue , Gems, Sixth Edition (2006)