A REVIEW OF ACHIEVEMENTS IN SCIENTIFIC RESEARCH OF REE MINERALOGY OF CHINA

摘要

There are more than one hundred species of REE (rare earth element) minerals known in China. Most of them have a minute description, such as chemical compositions, physical and optical properties, X-ray diffraction data, occurrences and mineral association. However, a small part of them is less studied and needs further work. The over hundred RE mineral species belong to the classes of fluorides, oxides, Ta-niobates, carbonates, fluorocarbonates, phosphates, arsenates, phosphate-carbonates, phosphate-silicates, silicates, titanium silicates, zirconium silicates and borosilicates. Among them, some are widely dispersed over the country, such as allanite, gadolinite and chevkinite of silicate, monazite and xenotime of phosphate, britholite of phosphate-silicate, bastnaesite and parisite of fluorocarbonate, aeschynite group, fergusonite group and euxenite group of Ta-niobate minerals. The occurrences of RE minerals, as a general rule, are controlled by geological processes. These widespread RE minerals are characterized by occurring in a wide range of conditions. They occurred in magmatic stage, different hydrothermal stages of post-magmatic stages, pegmatite stage and various metamorphic processes. As a result, these minerals are distributed over many localities and their occurrences are various as well. For the widespread RE minerals, the degree of their contributions is obviously controlled by the law of REE geochemistry and crystallochemistry of RE minerals. The former is mainly determined by the abundance of REE in the Earth crust, i.e. Clark's values, the later by the role of REE in the mineral crystals. For example, in the nature, allanite-(Ce) is widespread, but allanite-(Y) is less spread. Bastnaesite-(Ce) is widespread, but bastnaesite-(Y) less spread. In this case, it is evident that the law of REE geochemistry takes main effect. Besides, gadolinite-(Ce) is less spread, but gadolinite-(Y) is widespread. Fergusonite-(Ce) is less spread, but fergusonite-(Y) widespread. In this case, it is evident that the law of REE crystallochemistry in the minerals takes main effect. Furthermore, monazite as well as xenotime is widespread, and aeschynite-(Ce) as well as aeschynite-(Y) is widespread. In this case, it is quite evident that the laws of REE geochemistry and of REE crystallochemistry in the minerals both take effect.