quinoline derivatives, pyridine, and various alkyl homologues of pyridine, such as picoline and lutidine. Water concerns are sensitive issues in arid regions, such as the western U.S. and Israel's Negev Desert, where plans exist to expand oil-shale extraction despite a water shortage. Depending on technology, above-ground retorting uses between one and five barrels of water per barrel of produced shale-oil. A 2008 programmatic environmental impact statement issued by the U.S. Bureau of Land Management stated that surface mining and retort operations produce of waste water per of processed oil shale. In situ processing, according to one estimate, uses about one-tenth as much water. Environmental activists, including members of Greenpeace, have organized strong protests against the oil shale industry. In one result, Queensland Energy Resources put the proposed Stuart Oil Shale Project in Australia on hold in 2004. Extraterrestrial oil shale Some comets contain massive amounts of an organic material almost identical to high grade oil shale, the equivalent of cubic kilometers of such mixed with other material; for instance, corresponding hydrocarbons were detected in a probe fly-by through the tail of Halley's Comet in 1986. See also – a United States Geological Survey facility dedicated to preserving valuable rock-samples threatened with disposal or destruction — including oil shales – a well-analyzed marine oil shale found in the Baltic Sea basin – discussion of attempts to delay and minimize the impact of "peak oil" (the point in time of maximum global petroleum production), including the development of unconventional oil resources – discussion of global crude-oil supplies – a marine oil shale found in Tasmania – a lacustrine oil shale found in Scotland Spent shale References Bibliography </ref> External links Sedimentary rocks