Cause of Coloring of Anhydrite(Part 1)

Abstract

The coloring of anhydrite is generally attributed to calcium colloid., But this has not been previously established by accurate experiments on anbydrites of various colors., The color is not due to the difference of the constituent elements, for significant differences in chemical composition are shown neither by chemical analysis nor hy spectrum analysis., Also, Au which has often been regarded as the cause of coloring, is not detected even by spectrum analysis., The presence of calcium colloid, on the other hand, seems to be improbable, thouth not decidedly stated, by X-ray diffraction data and electron microscopic observations., From the author's opinion, the color in anhydrite is probably due to the presence of F-center and related phenomena., This hypothesis is supported by the results of discoloration in thermal experiments and visible light exposures, and the revival of color by X-ray exposures.,