Abstract: In order to further explore the mineralogical characteristics of glauconite in offshore sedi⁃ ments of Hainan Island，a series of physical and chemical tests such as actual observation，physical prop⁃ erties，optical properties，chemical composition and spectral characteristics of glauconite samples are car⁃ ried out according to its genetic mechanism，and a comprehensive analysis is carried out in combination with regional geological data.The results show that the glauconite is a typical authigenic mineral，and its material source is related to terrestrial materials. The chemical composition is potassium-rich and iron�rich magnesium-containing aquifer aluminosilicate，with a mica-type structure between dioctahedral and trioctahedral. Mineralogically，it belongs to disordered mixed-layer structure，which is mainly composed of illite/smectite mixed-layer minerals，and contains a small amount of illite，quartz，plagioclase，sider⁃ ite，hematite and calcite.The glauconite in the offshore sediments of Hainan Island is in the mature stage and has the properties of modern glauconite，which is of great significance for the development and utiliza⁃ tion of the occurrence sand mineral deposit.

Key words: glauconite, mineralogical characteristics, genetic studies, offshore sediments, Hainan Is? land