Geology of the Eureka pegmatite, Pennington County, South Dakota

Roy Eldon Roadifer

doi:10.3133/ofr54256

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Geology of the Eureka pegmatite, Pennington County, South Dakota

Roy Eldon Roadifer

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Abstract

The Eureka Pegmatite, two miles southeast of Keystone, Pennington County, South Dakota, is a small but possibly valuable zoned body containing more than 85,000 tons of coarse-grained granite-pegmatite rock. The mica in the pegmatite is probably not of any great importance, but the potash feldspar and beryl may comprise a considerable tonnage of valuable reserves. If the pegmatite can be exploited at a profit in spite of the graphite-damaged feldspar, it may yield substantial amounts of strategically important beryl by open-cut mining of the entire body. This report contains complete, megascopic mineralogical and structural details of the pegmatite, which are supplemented with drill core logs and a geologic map and cross-sections.

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Source-reported bounding extent: 42.479635° to 45.94531° latitude; -104.057698° to -96.436589° longitude. This indicates report coverage, not an exact sampling location. View area on OpenStreetMap.

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Roy Eldon Roadifer. 1954. Geology of the Eureka pegmatite, Pennington County, South Dakota. https://doi.org/10.3133/ofr54256

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