The discovery of coarse-grained uraninite in Kangdian Axis and its geological significance

The uraninite-bearing quartz veins from Haitain area of Miyi County along Kangdian Axis occur in the Wumaqing Formation consisting mainly of Late Proterozoic biotite-plagioclase schist, which was subjected to migmatization and controlled by ductile-brittle fault zone. Uraninite exhibits black and euhedral crystals composed of combination of cubes and octahedra as well as minor rhombic dodecahedra and cubes, with semi-metallic luster, from 0.5cm to 1cm in size. Mineral assemblage of uranium mineralization includes mainly quartz, uraninite, sphene and molybdenite. Researches show that uraninite formed in a high temperature and pressure geological environment in deep crust, derived from high temperature, acidic and reducing ore fluids. This discovery implies that Panxi area has especially favorable conditions for medium-high temperature hydrothermal vein-type uranium mineralization controlled by ductile-brittle faults in the migmatization region.