Uneven, Subconchoidal, ConchoidalArthur Thomas, Gemstones (2009), Uneven, Subconchoidal, Brittle, Metallic, Brittle, Metallic
Uneven, Conchoidal, ConchoidalArthur Thomas, Gemstones (2009)
Zn 2(AsO 4)(OH)Michael OâDonoghue , Gems, Sixth edition (2006)
Tourmaline is a series of several different minerals with unique chemical formulas. See The chemical formula of Tourmaline for details.