The color change of the pink and colorless LiAlSi₂O₆ spodumene crystal due to irradiation and heating is explained. The hypothesis about the change of Mn³⁺ to Mn⁴⁺ after irradiation was rejected. For the studied crystals, it was shown that both Mn²⁺ and Mn³⁺ occupy the M2 (not the M1) crystal site. Spodumene crystals which are primary pink (kunzite) contain Mn³⁺ (and Mn²⁺) at the M1 site. By contrast, those that become pink due to irradiation and heating contain Mn³⁺ and Mn²⁺ at the M2 site. The emission band of the former is 625 nm, and for the latter, it is 591 nm.

The dielectric properties of Ba_1−xCa_xTiO₃ (x = 0.17) ceramics were studied in a wide frequency range of 20 Hz–53 GHz. Diffused ferroelectric phase transition was revealed close to 339 K in the dielectric properties of ceramics. The behaviour of distributions of relaxation times in vicinity of the ferroelectric phase transition temperature is also typical for order-disorder ferroelectric phase transition. However, at lower temperatures (below 200 K), the most probable relaxation increased according to the Arrhenius law. At lower temperatures the maximum of the imaginary part of dielectric permittivity versus temperature strongly shifted to higher temperatures when the frequency increased (from 125 K at 1.21 kHz to 300 K at 33 GHz). This behaviour was attributed to the dynamics of Ti ions. The origin of the crossover from ferroelectric to relaxor behaviour of Ba_1−xCa_xTiO₃ (x = 0.17) ceramics is discussed in the paper.