Argillaceous earths, also known as clay, are a type of sedimentary rock that is composed primarily of clay minerals. Some synonyms for argillaceous earths include mudstone, shale, claystone, and siltstone. These rocks are formed from the accumulation of clay particles, which are typically carried by rivers, lakes, and other bodies of water. Argillaceous earths are often associated with oil and natural gas deposits, as their porous nature allows for the trapping and storage of hydrocarbons. They are also commonly used in construction, as clay is an excellent material for making bricks, tiles, and pottery. In addition, clay is used in many industrial processes, such as papermaking, ceramics, and cosmetics.