Clay is a natural, earthy, very fine-grained material largely composed of clay minerals. These minerals are hydrous layer silicates formed mainly from silica, alumina and water. Common clay minerals include Kaolinite, Al3Si2O5(OH)4, and Montmorillonite, (Na,Ca)(Al,Mg)6(Si4O10)3(OH)6-nH20. “Clay materials” is a broader term that includes shale and claystone in addition to clay. Clay and shale are mined in Virginia to produce structural clay products such as bricks, lightweight aggregate, cement, clay pipe and sewer pipe.
Approximately 1.4 million tons of clay and shale were extracted in 2003. Solite Corporation produces shale and slate for use as lightweight aggregate. Solite Corporation mines the Arvonia Slate in Buckingham County and mines shale from the Danville Triassic basin in Pittsylvania County. This lightweight aggregate is used primarily in masonry block and concrete for construction purposes.
Virginia ranks fourth in the United States in production of the montmorillonite variety of fuller’s earth. In 2003, approximately 52 thousand tons of fuller’s earth were mined in Virginia. Currently, two operations, one in King and Queen County and one in King William County, produce fuller’s earth for use primarily as cat litter. It is also marketed as an oil absorbent floor sweep material and as an animal feed supplement. Extraction of the fuller’s earth is by dragline. These deposits occur in the Tertiary-age Calvert Formation.
Clay material production, 1986-2003.
Selected References:Gilmer, A. K., Enomoto, C. B., Lovett, J. A., and Spears, D. B., 2005, Mineral and fossil fuel production in Virginia (1999-2003): Virginia Division of Mineral Resources Open-File Report 05-04, 77 p.
Virginia Division of Mineral Resources, 1993, Geologic Map of Virginia: Virginia Division of Mineral Resources, scale 1:500,000.