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Geologic map of the Triangle A pegmatite, Custer County, South Dakota Geologic map of the Triangle A pegmatite, Custer County, South Dakota

The Triangle A pegmatite is 4 miles southeast of Custer in the SW 1/4, sec. 34, T. 3 S., R. 5 E., Custer County, S. Dak. It may be reached from Custer by a gravel road 2.4 miles long that leaves U.S. Highway 16A at a point 3.2 miles east of Custer.
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