Brittle, Metallic, Brittle, Metallic
Uneven, Uneven, ConchoidalAnthony et al, Handbook of mineralogy (2001), Conchoidal, Uneven
Be 4Si 2O 7(OH) 2Anthony et al , Handbook of mineralogy (2001)
Mn 3B 7O 13ClMichael OâDonoghue , Gems, Sixth Edition (2006)