The latest issue of Acta Geologica Sinica (English Edition) reports that Li Ziying, head of the China National Nuclear Corporation’s Beijing Uranium Geology Research Institute says there are new uranium discoveries that can help in understanding hydrothermal uranium mineralization and uranium formation and the evolution of the earth's heat.

A research team used photoelectron spectroscopy to do a systematic study of the composition and valence of China’s typical hydrothermal uranium deposits and found uranium with a valence of 4 or 6, and metallic uranium with a valence of 0. Uranium is widely scattered around the earth, but exists in compounds because of its instability and valences. It has long been believed that there is no metal uranium in nature so this is the first time to find metallic uranium naturally.

Uranium in hydrothermal deposits comes from deep inside the earth and exists in metal form or with low valence. Most of uranium exposed to oxygen has a valence of 4 or 6, with only a part of it still in a metallic state. Li explains that a valence of 0 or 4 or 6 in hydrothermal uranium ore could indicate the depth at which it formed and could be a key to understanding the mechanism and controlling factors of hydrothermal uranium mineralization, and that this is significant for pure research and application. This latest sample came from two uranium deposits in northern Guangdong province.

Photoelectron spectroscopy is an important analysis technology and can detect the chemical composition of a material’s surface, and its valence as well.