Mineralogic investigation into occurrence of high uranium well waters in upstate South Carolina, USA

► Oxidative dissolution of uraninite in biotite granite is primary source of uranium in high-U well waters near Simpsonville, SC. ► Uranium is chiefly transported as mixed uranyl hydroxyl-carbonate complexes. ► Local reduction has resulted in secondary precipitation of uranium along fractures as coffinite. ► Dissolution of uraninite and precipitation of coffinite were geologically recent.