油页岩是富含有机物的沉积岩，粒度小，主要成分为油母质（由有机化合物组成的固态混合物），可自其提炼出液态烃类。虽然名为「油页岩」，但事实上地质学家并不全然将之归类为页岩，且油母质与石油并不相同。油母质的加工成本比石油高，因此就价格及环境冲击方面而言，油母质常被视为石油的替代品。页岩油沉积层分布于全球各地，估计所有沉积层共储有2.8兆至3.3兆桶（450×10 至 520×10立方公尺）可采油量。

透过裂解化学变化，可将油页岩中的油母质转换为合成原油。加热油页岩至特定温度能将分离蒸气，即借由蒸馏产生类似石油的页岩油——一种非传统用油——以及易燃的油页岩气（「页岩气」亦可指页岩内含的天然气体）。工业单位也直接燃烧油页岩作为发电或供暖的劣等燃料。油页岩另也被用作化学原料、建筑工程用途等。

Oil shale, also known as kerogen shale, is an organic-rich fine-grained sedimentary rock containing kerogen (a solid mixture of organic chemical compounds) from which liquid hydrocarbons called shale oil (not to be confused with tight oil—crude oil occurring naturally in shales) can be produced. Shale oil is a substitute for conventional crude oil; however, extracting shale oil from oil shale is more costly than the production of conventional crude oil both financially and in terms of its environmental impact. Deposits of oil shale occur around the world, including major deposits in the United States. Estimates of global deposits range from 4.8 to 5 trillion barrels (760×10^ to 790×10^ m) of oil in place.