Uneven, Conchoidal, ConchoidalArthur Thomas, Gemstones (2009)
UnevenArthur Thomas, Gemstones (2009), UnevenArthur 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 2Mg 5Si 8O 22(OH) 2Ulrich Henn and Claudio C.