Purple-cathodoluminescent calcite associated with periclase and survival dolomite has been found from the skarn minerals in the Kanehira mine located in the eastern part of Hiroshima Prefecture. Paragenesis of these minerals suggests that the decomposition of dolomite at 700-750°C under dry condition during skarnitization could promote the production of characteristic calcite. Cathodoluminescence (CL) spectroscopy of the calcite reveals its blue emissions related to defect centers possibly derived from its origin, also similar CL features in the dolomite. Spectral deconvolution of the CL in the calcite and dolomite clarified two emission components at 2.67 and 3.30 eV, of which former corresponds to structural defect by thermally-influenced stress and the latter to intrinsic defect comparable to 'back ground blue' previously reported in calcite. The facts imply that the calcite with purple CL might leave the defects in its structure during thermal decomposition of dolomite at relatively high-temperature skarnization.

Smithsonite occasionally exhibits a characteristic blue emission, known as cathodoluminescence (CL), which can be assigned to a lattice defect center by CL spectral analysis. The intensity of this emission is reduced at higher temperatures, suggesting a temperature quenching phenomenon. The activation energy in the quenching process was evaluated by a least -square fit of the Arrhenius plots using the integrated intensity of the emission component, and was found to be ~ 0.03 eV for the defect center. According to the Mott -Seitz model, the quenching process can be interpreted by an increase in non -radiative transition at higher temperatures. The value of the activation energy for a blue emission caused by the defect center corresponds to the vibration energy of the O -Zn -O bending mode in the lattice. It implies that the temperature quenching energy might be transferred as a phonon to the specific lattice vibration.