Pegmatites and alkali feldspar granites as sources of industrial k-feldspar: a study from Borucu, Aksaray, Central Türkiye

The Borucu (Aksaray) region, within the Central Anatolian Crystalline Complex, comprises a variety of rocks, including granite, alkali feldspar granite (AFG), pegmatite, and aplite dikes. The granite and AFG host some veins or lenses of pegmatites, with lengths reaching approximately 70 m in the N10-25W direction. The AFG and pegmatitic rocks are characterized by variable mineral assemblages, including K-feldspar (orthoclase), quartz, plagioclase, and to a lesser extent, biotite, garnet, and opaque minerals. Inner zones feature the mega-grained pegmatite, whereas outer zones consist of the coarse-grained K-feldspar and quartz pegmatite. In this study, integrated surface and vertical (trenching and drilling) exploration, mineralogy-petrography, geochemical, and magnetic separation analyses were employed to assess the industrial raw material potential of the AFG and pegmatites. The total alkali (Na2O+K2O) contents reach in 15.56-16.82% for the mega-grained pegmatite, 8.07-9.76% in the coarse-grained pegmatite, and 9.20-9.66% in the AFG. However, the Fe2O3 contents (0.30-1.15%) constrain their industrial raw material quality. Magnetic separation improved the AFG material to second-quality ceramic industry standards. Despite Fe2O3 limitations, Borucu’s pegmatites and AFG represent usable industrial raw material resources.