Uranium and phosphate resources in the Cooper Formation of the Charleston region, South Carolina

Phosphate deposits formerly exploited in the Charleston district were formed by weathering and reworking of the Cooper Formation (Eocene and Oliogcene). Previous workers have shown that unusual concentrations of uranium occur in phosphate-rich nodular material formed during subareal weathering. We found that the old mining district is on an erosional high of the Cooper Formation and in a topographic depression, but that the process of weathering enrichment of the Cooper Formation extends beyond the mining district.

Fresh sediments from the Cooper Formation average 14.5 ppm uranium and 1.0 percent P₂0₅ for Oliogcene samples and 5.6 ppm U and 0.15 percent P₂0₅ for Eocene samples. Zones of secondary enrichment over undifferentiated Cooper Formation average 2 m thick and have average values of 60 ppm U and 5.4 percent P₂0₅. No deposits clearly of economic importance were found, although detailed studies may reveal such deposits.