Geochemical sampling of bedrock has revealed anomalous copper, silver, molybdenum, gold, arsenic, mercury, zinc, and cobalt in meta-iron-formation in the Blue Lead Mountain area 5 miles (8 kilometres) north-northwest of Keystone, S. Dak. The anomalies are in complexly folded and faulted iron-formation. Metal content decreases sharply in the surrounding rocks. The extent and intensity of the anomalous areas, despite evidence that previous mining had little success, are sufficient to make this area an interesting target for exploration.
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Anomalous concentrations of several metals in iron-formation of the Blue Lead Mountain area, Pennington County, South Dakota