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
SiO 2Ulrich Henn and Claudio C.
Mn 3B 7O 13ClMichael OâDonoghue , Gems, Sixth Edition (2006)