During World War II Roberts lived in Central America, where he had been sent to discover and conduct fundamental research on strategic minerals. After the war he returned to the United States; for the next 40 years he worked in Nevada and Utah, deciphering the geologic history of major mountain ranges and exploring mineral deposits. In 1960, Roberts published a paper that predicted the existence of important mineral-bearing rocks in Nevada. Roberts' research led to the discovery of the Carlin and Cortez-Battle Mountain gold belts. These two mining districts now represent the richest gold region in the United States, and one of the leading gold producing regions of the world. During the 1970s he spent six years in Saudi Arabia, mapping ore deposits and contributing to the development of the Arabian mining industry. He retired from the USGS in 1981, but continued his mineral exploration in Nevada for over two decades.
Roberts, Ralph Jackson. "Quicksilver deposits of the Bottle Creek District, Humboldt County, Nevada"
Roberts, Ralph Jackson. "Quicksilver deposit at Buckskin Peak National mining district, Humboldt County, Nevada"
Roberts, Ralph Jackson. "Manganese deposits in Costa Rica"
Roberts, Ralph Jackson. "Geology of the Antler Peak Quadrangle, Nevada". USGS Open-File Report 49-47
Roberts, Ralph Jackson, Irving, E.M. "Mineral deposits of Central America"
Roberts, RJ, Holtz, PE, Gilluly, J, and Ferguson, HG. "Paleozoic Rocks of North-Central Nevada". AAPG Bulletin, v 42, #12, pp 2813-2857
Roberts, Ralph Jackson. "Stratigraphy and Structure of the Antler Peak Quadrangle, Humboldt and Lander Counties, Nevada"
Roberts, Ralph Jackson. "The genesis of disseminated and massive sulfide deposits in Saudi Arabia"
Luce, Robert W., Bagdady, A., Roberts, R.J. "Geology and ore deposits of the Mahd adh Dhahab district, Kingdom of Saudi Arabia"
Roberts, Ralph Jackson, Rye, R.O., Mawad, M.M. "Preliminary sulfur isotope investigations of mineral deposits in the Precambrian shield, Kingdom of Saudi Arabia" USGS Open-File Report No. 78-776
Roberts, Ralph Jackson, Bagdady, A., Luce, R.W. "Geochemical investigations in the Mahd Adh Dhahab District, Kingdom of Saudi Arabia" USGS Open-File Report No. 78-777
Bagdady, A.Y., Whitlow, J.W., Roberts, R.J. "Placer gold deposits in the Mahd Adh Dhahab district, Kingdom of Saudi Arabia" USGS Open-File Report No. 78-1074
Martin, Conrad, Roberts, R.J., Stoeser, D.B. "Titaniferous magnetite in the layered intrusive complex at Lakathah, Kingdom of Saudi Arabia"
Roberts, Ralph Jackson. "Iron sulfide deposits at Wadi Wassat, Kingdom of Saudi Arabia"
Later life
In 2002, Roberts published his autobiography, entitled A Passion for Gold.