Carbonatite-alkaline complex-associated rare earth element (REE) deposits are the principle sources of REEs. The enrichment and mineralization processes of REEs during such magmatic-hydrothermal systems are currently the most highly debated issues in metallogenic studies. Due to the widespread occurrence of bastnäsite and monazite in nature, most studies are focused on the mineralogical and geochemical properties of REE phosphates and fluorcarbonates. Unfortunately, experiment results demonstrate that the solubilities of REE phosphates and fluorcarbonates are insufficient for the formation of REE mineralizing fluids. By contrast, REEs also occur as Na-rich REE carbonate minerals in carbonatites, including carbocernaite and burbankite. These minerals are formed from some unique fluids, meanwhile easily altered during later hydrothermal processes, hence attracting limited research interests. However, according to the results from latest experiments, the transition from bastnäsite to carbocernaite via reacting with Na⁺ and CO^2-₃ is the essential process that leads to the exceptional enrichment of REEs in aqueous liquids. Furthermore, REEs precipitate preferentially as carbocernaite or burbankite from Na-enriched carbonate fluids, and crystallization of bastnäsite occurs either during a relatively early stage where Na is insufficiently enriched, or after Na precipitating substantially as alkaline silicate minerals during interaction with silicate wall rocks. These findings are consistent with REE occurring as burbankite in isolated systems (such as fluid inclusions), but as bastnäsite in carbonatite ore veins or other open systems, and indicate that such Na-rich REE carbonate minerals have clear implications for REE mobilization and mineralization processes. In this paper, we reviewed the crystal structures and chemical properties of carbocernaite and burbankite, and compared the occurrence of both minerals in carbonatite REE deposits to those in high pressure-temperature experiments, aiming to reveal the roles of such minerals during REE mobilization and mineralization processes, and provides clues for establishing a comprehensive REE metallogenic model in carbonatite systems.