Abstract <p>The natural radioactivity in rock and dependence of the radioactivity on the mineralogy of rocks in the Dharwad region of Karnataka, India, were studied. The radionuclide activity in rocks was analyzed using a NaI(Tl) gamma-ray spectrometer, and the mineralogy was studied using FTIR spectroscopy and X-ray diffraction. The activity concentrations varied from 105 ± 2 to 783 ± 7 Bq kg^–1 for ⁴⁰K, from 2 ± 0.5 to 63 ± 2 Bq kg^–1 for ²²⁶Ra, and from 10 ± 1 to 65 ± 2 Bq kg^–1 for ²³²Th, with mean activity of 511 ± 6, 31 ± 2, and 39 ± 1 Bq kg^–1, respectively. The activities of natural radionuclides were found to be slightly higher for ⁴⁰K and ²³²Th but lower for ²²⁶Ra. The radiation hazard indices were determined to assess the radiation exposure of the region’s population. The study showed that elevated ⁴⁰K and ²³²Th levels in the region are due to the presence of potassium-rich biotite, silicate-bearing feldspar, and phosphate mineral monazite present in the rocks of the region.</p>