Naturally synthesized fluorite crystals were investigated in terms of their spectroscopic characteristics to indentify the origin of their colors and dynamics of color variation induced by electron-beam irradiation. Specimens with various colors and shades categorized into four groups were irradiated by an electron beam with two different power densities and subsequently heat-treated at various temperatures and times to investigate the kinetics of the color change process. Various aspects of spectroscopic characteristics before/after e-beam irradiation and heat treatment were analyzed by comparative studies by a UV-V is spectrophotometer, a Fourier transforminfrared spectrometer, an X-ray fluorescence spectrometer, X-ray diffraction, and a photoluminescence spectrometer. The variety of color groups of natural fluorite samples were confirmed to be caused by various defects and F-centers generated by e-beam irradiation.

Keywords: Natural fluorite, Electron-beam irradiation, F-center.