Preliminary map of columbium (niobium) and tantalum provinces in the conterminous United States

Online link https://pubs.usgs.gov/of/1979/0576n/plate-1.pdf
Description Scanned image of map drawn at 1:5,000,000 scale, projection probably Lambert Conformal Conic, monochrome.
Originators Tooker, Edwin Wilson and Parker, Raymond Laurence
Publication U.S. Geological Survey Open-File Report 79-576

This publication is available only as a PDF document.