13 samples were analyzed by XRD, 6 by XRF (major elements, sulfur), and 2 pisolitic samples mapped by EPMA (Al, Fe, Ca). XRD showed boehmite only in pisolitized cores, with other samples dominated by well-ordered kaolinite plus minor hematite, alunite and anatase; basal-section clays showed well-ordered kaolinite with unaltered K-feldspar and volcanic glass, while upper parts were more weathered (Fe/bauxite-rich).
Files included in this product
Mineralogy and chemistry of bauxitic clay deposits of the Salt Range were studied via a field visit sampling bauxite/clay deposits mined from the Hangu Formation at Khewra, Katha and Sultan Mehdi. 13 samples were analyzed by XRD, 6 by XRF (major elements, sulfur), and 2 pisolitic samples mapped by EPMA (Al, Fe, Ca). XRD showed boehmite only in pisolitized cores, with other samples dominated by well-ordered kaolinite plus minor hematite, alunite and anatase; basal-section clays showed well-ordered kaolinite with unaltered K-feldspar and volcanic glass, while upper parts were more weathered (Fe/bauxite-rich). XRF showed Al/Si close to ideal kaolinite, with Al up to 58 wt.% in bauxite-rich samples. The kaolinite deposits formed by weathering/alteration of andesitic volcanic ash under humid/temperate conditions, evidenced by upward-increasing weathering intensity and Si depletion with Al/Fe enrichment; anatase (TiO2>1 wt.%) requires separation during processing of basal/middle deposits, but upper-part processing is not economical
