Mineralogy of oil shale

Mineralogical investigations of oil shales are few and do not permit detailed geologic interpretation of the environment of formation. In general, oil shales are low-energy sediments, usually deposited under reducing conditions in large lake basins, on continental platforms and shelves in quiet seas, and in small lakes, bogs, and lagoons associated with coal-forming swamps. There is abundant geologic data on the Green River oil shale, but these deposits are not necessarily representative of oil shales in general. Deposition of the Green River Formation occurred in the Eocene Gosiute—Uinta lake system during one of three climatic episodes. It is composed of detrital and authigenic clays, carbonates, and silicates. Much future geological and geochemical investigation of oil shales is warranted to establish the details of oil-shale genesis and provide a meaningful genetic classification of oil-shale deposits. Particularly fruitful research topics appear to be (1) detailed sedimentological study, (2) descriptive petrographical and mineralogical investigations of oil shales from various parts of the world, (3) geochemistry of evaporite minerals and altered volcanic rocks, and (4) clay mineral analysis of various oil shales.