The federal Bureau of Mines conducts a comprehensive test program on clay and shale at the Tuscaloosa Metallurgy Research Center. All samples are subjected to standard preliminary ceramic tests, which include firing formed briquets at temperatures ranging from 1,000 deg to 1,250 deg c to identify firing range and colors, and quick- firing to determine bloating characteristics. Materials that show potential as structural products are further tested after either extrusion or dry-pressing. If the quick-fire test is positive, bulk samples can be fired in a rotary kiln to evaluate their potential as lightweight aggregate. A number of miscellaneous tests also can be conducted if requested. These tests determine properties such as refractoriness (pyrometric cone equivalency), oil-bleaching characteristics, oil absorbency, viscosity for drilling-mud applications, sand-bonding properties for foundry usage, and pelletizing characteristics.