Clay and Shale
File:Black Ohio Shale Artifact.jpeg|
Large, smooth, rounded stone artifact is roughly triangular in shape. On one side there are incised lines in a crosshatch pattern. On the other side there are incised lines that depict a serpent-like creature with large teeth, a fish-like tail and exaggerated spines decorated with crosshatching. A zigzag line is drawn from the eye to the heart. The artifact is made from black Ohio shale. It has been broken into three pieces and glued together. Item was found in Clay Township, Scioto County, Ohio.
Clay is composed of very fine-grained clay minerals, is not layered and has a plastic consistency. Clay deposits in Ohio were formed as ancient soils beneath coal beds (underclays) of Pennsylvanian age or deposited in glacial lakes during the Pleistocene Ice Age. Shale is a fine-grained rock composed of clay minerals but differs from clay primarily because it is bedded (layered).
Ohio ranks fifth in production of clay and shale with a total value of about $11.9 million from 2.24 million tons of annual production. Clay is produced in 19 counties and shale in 18 counties. Pennsylvanian-age underclays are present in the eastern half of the state whereas production from Pleistocene deposits is from the western part of the state.
Ohio has long been a center of the clay and shale industry. During the 1900s and early 1900s many companies produced brick, common clay products such as sewer tile, and decorative ceramic pottery. Although many of these companies have ceased operation, Ohio clays and shale are still used to produce brick, tiles, ceramics, as a component of cement, and in the manufacture of paper, cosmetics, and many other products. Much of the clay mined is used as liners for landfills and ponds.