U.S. Bureau of Mines Wyoming Corehole No. 1 drilled near Eden in Wyoming's Green River Basin sampled Green River Formation oil shales representing a potential of 200 million bbl of oil per sq miles. In general properties and gross mineralogy, the sampled oil shales strongly resemble Mahogany-zone oil shales of Colorado and Utah. Alternating thin beds of tough, rich oil shale and brittle, lean oil shale at depths less than 700 ft may offer advantages to in place shale oil production techniques, providing possible access to at least 100,000 bbl of shale oil per acre in an area greater than 100,000 acres. (16 refs.)