Uneven, Conchoidal, ConchoidalArthur Thomas, Gemstones (2009)
Uneven, Uneven, ConchoidalArthur Thomas, Gemstones (2009), Conchoidal, Brittle
Tourmaline is a series of several different minerals with unique chemical formulas. See The chemical formula of Tourmaline for details.
Ca 3Al 2(SO 4)(F,OH) 10Ulrich Henn and Claudio C.