The Eocene Green River Formation, forming the slope in the background, contains most oil shale reserves in that state, near Parachute, Colorado, September ©2019 hopkins/neoscenes.

Oil Shale

Colorado has the world’s largest resources of oil shale, by far. Oil shale is actually the rock marlstone which contains kerogen, a precursor to oil. The kerogen must be heated to more than 750 degrees to convert it into oil because it was never buried deeply enough for nature to convert the kerogen to oil.

People have been trying to economically produce oil from this rock for more than a century. Indeed, the CGS issued a report in 1921 entitled, Oil Shales of Colorado. Thus far, technological and economic conditions have not combined to support a sustained oil shale industry in Colorado.