【摘要】 <正> 天然萤石是自然界中颜色品种最多的矿物,由于萤石的染色机制能说明矿物的形成条件和生长历史,并能决定萤石在光学和技术上的应用,所以研究萤石的染色机制十分必要。H.Bill和G.Galas 1978年曾系统总结了萤石的染色理论,其中详细讨论了与稀土离子和氧有关的色心,强调指出辐射会导致色心集结而析出胶体钙。R.W.T.Wilkins又从缺陷、杂质、胶体钙三个方面讨论了萤石的紫色起因。本文对产于我国白云鄂博矿区的蓝(紫)更多还原

【Abstract】 The color-causing mechanism of fluorite from Bayan Obo has been studied by means of optical absorption analysis, NMR, chromatography, electron microscopy, thermo-stability and artificial irradiation experiments, and semi-quantitative speetrographic analysis and chemical analysis. The results show that there is a close correlation between the distribution of color and the lattice damage caused by radioactivity. Obvious differences between U and Th contents and defect densities in different color regions of the fluorite were determined. In addition, the thermo-stability and characteristic optical absorption bands of the fluorite were observed as well. In the light of the above data,it is concluded that the main color-causing material is colloidal caleium trapped in the lattice defects of the crystal. It is considered that the colloid may be formed as the result of the concentration of calcium atoms escaping from the lattice during long-term irradiation by radioactive elements in the geological environment where the fluorite was formed. Partial destruction of the fluorite structure is also a very important factor responsible for lattice defects. The color bands are attributable to periodic fluctuations in the composition of mineralizing solutions and the physical conditions of mineralization.更多还原