Diopside, a natural silicate mineral of formula CaMgSi2O6, has been investigated concerning its thermoluminescence (TL) and electron paramagnetic resonance (EPR) properties. Glow curves and TL vs. γ-dose were obtained irradiating natural samples to additional dose varying from 50 to 10,000 Gy. Except for a 410 °C peak found in the Al-doped artificial diopside, all the other peaks grow linearly with radiation dose, but saturate beyond ∼1 kGy. To investigate high-temperature effect before irradiation, measurements of TL intensity in samples annealed at 500-900 °C and then irradiated to 1 kGy γ-dose were carried out. Also the TL emission spectrum has been obtained. To compare with natural diopside, a synthetic pure polycrystal was produced and further those doped with iron, aluminum and manganese were also produced. © 2007 Elsevier B.V. All rights reserved.