We investigated Late Permian Li-rich claystones with up to 1.05 wt% Li₂O (average: 0.45 wt% Li₂O) in the Pingguo area in Guangxi, southwest China. Our results show that cookeite (chlorite group) is the dominant Li-bearing mineral. Cookeite is intercalated with authigenic illite and detrital kaolinite, which suggests that cookeite formed during burial diagenesis from pre-existing Li-rich kaolinite in the original clay assemblage. The Li-rich claystones were mainly sourced from felsic volcanic rocks of the Emeishan large igneous province (LIP), and the Li-rich kaolinite was likely produced by weathering of felsic volcanic materials (i.e., pyroclastic rocks, tephras, and volcanic glass) deposited on a Permian carbonate platform. We propose that the abundance of precursor kaolinite and its Li content control the degree of Li enrichment in this new potential Li resource.