[en] For this classification, uranium deposits in sedimentary rocks are divided into two groups, syngenetic and epigenetic: syngenetic deposits are formed contemporaneously with deposition of the enclosing sediment; while epigenetic deposits are formed by precipitation of uranium from solutions moving through pre-existing rock or previously deposited sediment: The five classes of syngenetic deposits are as follows: placer, quartz-pebble conglomerate, marine black shale, phosphorite, and water. Epigenetic deposits include lignite, coal, and carbonaceous shale; evaporative precipitates; sandstone; and limestone