Abstract:A study on existing valence state and chemical behavior of cerium element in two categories of rock weathering system in China has been carried out. In the granitoid weathering crust of Southern China, cerium as tetravalent hydroxide absorbed on clay minerals occupies 62.58% of total amount of cerium and the cerium partitioning in the phase is 69.58%. The depositing cerium stops its mobility downward, resulting in rare earth partitioning variation, the light rare earth partitioning is high at upper layer of weathering crust, the heavy rare earth partitioning is high at bottom layer of weathering crust, and the extracted product exists cerium lose effect. For Mn²⁺ as reducing agent existing in black weathering earth of Maoniuping rare earth ore, cerium is trivalent and absorbed on Mn-Fe oxide as colloid phase sediment. Colloid sediment phase can be divided into Mn-Fe combined phase and hydroxide sediment phase with cerium contents of 19. 77% and 48.30%, and their cerium partitionings are 80.72% and 37.38% respectively. The Mn-Fe combined phase can selectively absorb cerium.

Key words: cerium　rare earth ore　weathering system　chemical behavior