Attempts to extract shale oil in the 1970's in the western US, some of the richest deposits in the world, cost several billion dollars and failed to produce an economically viable process.  Many countries have quantities of oil shale: Australia, Brazil, Canada, China, Estonia, Russia, Scotland, South Africa, Spain Sweden and the United States of America which has 62% of the potentially recoverable oil shale.  Oil shale (between 5 and 25 percent of the rock) must be crushed and heated to 500 degrees Celsius to be changed into an oil-like liquid which must be processed but can produce an oil better than the lowest grade of oil produced from pumping.  Immense amounts of shale spoil in the form of coarse sand is left behind from the mining which must be large scale.   The process .