Gypsum is a hydrated calcium sulfate: CaSO₄·2(H₂O).  It is commonly used for making plaster, wallboard and in the production of portland cement. 

Year of first production in Virginia: around 1890
Location of first production in Virginia:  Smyth and Washington Counties
Year of last production in Virginia: 1999
Location of last production in Virginia:  Smyth County

Gypsum was extracted from the Mississippian-aged MacCrady Formation (~350 millions years old), where it occurred as isolated masses surrounded by gray shale and red clays.  U. S. Gypsum, the nation’s largest wallboard producer, closed its Locust Cove mine near Rich Valley in Smyth County in 1999.  It supplied gypsum to a wallboard plant in nearby Plasterco, Virginia.  The mine was a slope-entry underground mine that extended more than 800 feet below the surface.  The mine utilized the modified room-and-pillar sublevel stopping mining method.  Final production in 1999 was approximately 304 thousand tons.

 

Gypsum production, 1983-1999.

 

 

Selected References:
Cooper, B. N., 1966, Geology of the salt and gypsum deposits in the Saltville area, Smyth and Washington Counties, Virginia, in Rau, J. L., editor, Second Symposium on Salt, v. 1, Geology, Geochemistry, and Mining: Northern Ohio Geological Society, Cleveland, 34 p.

Eckel, E. C., 1902, Salt and gypsum deposits of southwestern Virginia: Contributions to Economic Geology, 1902, U. S. Geological Survey Bulletin 213, p. 406-417.

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.

Watson, T. L., 1907, Mineral Resources of Virginia: Lynchburg, Virginia, Jamestown Exposition Commission, 618 p.
(available as Virginia Division of Mineral Resources, 2003, Digital reprint of T. L. Watson’s 1907 Mineral resources of Virginia: Virginia Division of Mineral Resources Publication 175, [CD-ROM; 2003, September 1].

Whisonant, R. C., 1996, Geology and the Civil War in southwestern Virginia: The Wythe County lead mines: Virginia Minerals, v. 42, n. 2, p. 13-19.