[en] The natural mineral blue kyanite (Al₂SiO₅) crystals were investigated in terms of thermally stimulated luminescence, optical absorption and electron paramagnetic resonance measurements. The glow curves for natural samples present two glow peaks at 155 deg. C and 220 deg. C. Pre-annealed and subsequently irradiated samples give rise to four glow peaks at 160 deg. C, 210 deg. C, 285 deg. C and 360 deg. C. The observed EPR spectra revealed the presence of Fe³⁺ ions in the crystalline matrix and a change in its valence state is predicted on irradiation. Also E₁' centers and hole type centers are induced on irradiation. A mechanism for the observed thermoluminescence is suggested