Industrial Minerals Deposits

APPLIED PETROGRAPHICS has extensive experience in the exploration , field, and laboratory evaluation of feldspar, nepheline syenite, and quartz deposits and their processed products.

  • Identification and characterization of suitable ore units
  • Determination of deposit consistency and uniformity
  • Characterization of texture and amenability to separation of ore mineral components
  • Product characterization
  • Determination of the presence and distribution of deleterious components
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    Identification and characterization of suitable ore units
    (TLX)

    		(CL)

    The Spruce Pine, North Carolina alaskite deposits provide commercial feldspar and high-purity quartz sources for several companies, including Unimin, Zemex, and K-T Feldspar. The sample is shown in both transmitted light/crossed polars (TLX) and under CL. The sodic orthoclase has light blue CL from Ti4+ activation, while the quartz is non-luminescent.
    (TLX) Distribution of deleterious components (CL)
    This coarse-grained nepheline syenite is unsuitable as a source for commercial nepheline syenite product. Although it is texturally simple and yields a good feldspar-nepheline concentrate, the concentrate has an elevated Fe2O3 abundance (>0.4% Fe2O3). The red CL of the orthoclase in the right photo is due to Fe3+ activation. Subsequent electron microprobe analyses showed Fe2O3 abundances of up to 0.9% in nepheline and 0.4% in feldspar. Significant funds were expended on project prior to the performance of the petrographic and analytical work.
    Deposit exploration and characterization
    Syenite phase from the Canaa nepheline syenite deposit in Brazil. The CL photo at left shows K feldspar with light blue CL (Ti4+ activation) overprinted by red CL (Fe3+ activation) owing to deuteric alkali-ferric iron metasomatism. The plagioclase has darker blue CL. Calcite has bright orange CL. The K feldspar overprinted by red CL has Fe3+ substitutional in the crystal lattice for Al3+. The same view in the TLX photo at right shows an unaltered syenite, but provides no information regarding the presence and distribution of deleterious Fe3+ in the K feldspars.
    (CL)Texture and amenability to separation (CL)
    Coarse-grained syenite (left) and feldspar product (right) from a Mexican feldspar deposit. The CL photomicrographs show the distribution of Fe3+ substituting for Al3+ in the orthoclase microperthite crystal lattice. Fe3+ activated feldspar has red CL and results from late-stage deuteric alkali-ferric iron metasomatism in the syenite source rock. The feldspar product contains 0.232% Fe2O3 and should be competitive in the Mexican market.
    (CL) Product characterization (TLX)
    This feldspar product was processed from a granodioritic source rock. It contains K feldspar and plagioclase and has an Fe2O3 abundance of 0.05%. The CL photo at left shows the distribution of K feldspar (light blue CL), unaltered plagioclase (light green CL), and clay-altered plagioclase (reddish brown CL).
    Identification of contamination in a quartz product
    Backscattered electron (BSE) imaging of quartz concentrate products showing the disposition of contamination by feldspar. The quartz is gray, while feldspars are white. Optimization of flotation parameters can remove contaminant feldspar present either as discrete grains or as composite locked grains with feldspar and quartz in sub-equal abundance. Bits of feldspar adherent to the margins of quartz grains may present a problem if an extremely pure quartz product is required.