The Chemical Composition of Granite-Related and Mineralization-Related Tourmaline in Nova Scotia
Reardon, Nancy C.
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Tourmaline is a common accessory mineral which occurs in a wide variety of mineralogical settings. This mineral is commonly found in sedimentary, metamorphic, and granitoid intrusive rocks and their associated aplites, pegmatites and hydrothermal aureoles (greisens). Tourmaline is also frequently found in association with many types of mineral deposits. These include massive sulfides, polymetallic sulfides, vein and breccia Sn, vein Au, Sn and Mo greisens and Be-Li pegmatites. The chemical composition of tourmalines from occurrences of these types in Nova Scotia has been determined by microprobe analysis for SiO2, TiO2, Al2O3, FeO, MnO, MgO, CaO, Na2O, K2O and F. Both cores and rims of all grains were analyzed to determine possible chemical zoning; many grains show colour zoning. These analyses have shown distinct relationships exist between tourmaline composition and geological setting, however, significant overlap occurs among many of the groups studied. Chemical compositions and trends seen on binary plots for the elements analyzed are similar to those observed for tourmaline occurrences elsewhere. Boron isotope analyses were also carried out, however, no relationship between tourmaline paragenesis and boron isotope composition is evident. Keywords: Pages: 144 Supervisor: D. Barrie Clarke