Sub-Conchoidal, Irregular/uneven, Sub-Conchoidal, Uneven, ConchoidalArthur Thomas, Gemstones (2009), ConchoidalArthur Thomas, Gemstones (2009)
Uneven, Conchoidal, ConchoidalArthur Thomas, Gemstones (2009)
(Li,Na)Al(PO 4)(F,OH)Michael OâDonoghue , Gems, Sixth edition (2006) More from other references
Tourmaline is a series of several different minerals with unique chemical formulas. See The chemical formula of Tourmaline for details.