Gems, Conchoidal, Brittle
ConchoidalWalter Schumann, Gemstones of the world (2001), ConchoidalWalter Schumann, Gemstones of the world (2001), Brittle, Metallic
Ca 3Ti4+2(Fe3+2Si)O 12Michael OâDonoghue , Gems, Sixth Edition (2006) More from other references
BeAlSiO 4(OH)Michael OâDonoghue , Gems, Sixth Edition (2006) More from other references