Glauconite has long been considered to be an authigenic mineral formed at specific marine conditions and thus an indicator mineral of marine facies. Nevertheless, with the successive discovery of continental glauconite, it seems necessary to reconsider this viewpoint. Based on statistics of glauconite from different areas and different environments, it is held that glauconite is formed either in marine environment or in continental lake environment, and hence cannot be regarded as a facies mineral. Compared with that formed in marine environment, glauconite formed in continental lake environment is generally characterized by high Al2O3, K2O and low FeO.