Vermiculite

Vermiculite is a hydrated magnesium-iron-aluminum silicate: (Mg,Fe++,Al)₃(Al,Si)₄O₁₀(OH)₂·4(H₂O).  It is used as a fertilizer carrier, as a lightweight concrete additive, as an industrial absorbent, and in fireproof insulation and sound insulation. 

Location of first production in Virginia:  Louisa County
Year of last production in Virginia:  currently producing
Location of current production in Virginia:  Louisa County
Total current annual production:  in 2003, 34,391 tons

One company, Virginia Vermiculite LLC, produces vermiculite in Virginia.  The company operates an open pit mine near Trevilians, in Louisa County.  This is one of only three active vermiculite mines in the United States (Potter, 2003).  The deposit is in an 80- to 100-foot thick weathered zone in mafic rocks of the Green Springs pluton.  The soft ore is excavated with earth moving equipment, then washed and milled.  The vermiculite is separated from other minerals by froth flotation, and is then dried and screened to produce four different sizes of product.

Annual production peaked in 1999 at 48,256 tons.  Since then, production has decreased somewhat to 34,391 tons in 2003.  Average annual production from 1999 to 2003 was 39,211 tons.  Vermiculite’s increasing use in building applications and in fireproofing processes may account for the large increase in its price in 2002.  The U.S. Geological Survey reports a 2003 market price of $143 per ton for vermiculite. Vermiculite is known to occur in several counties in Piedmont province of Virginia, including Buckingham, Bedford, Pittsylvania, Franklin, Henry, Louisa, Charlotte, and Halifax Counties (Gooch, 1957).

Vermiculite production and value, 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.

Gooch, E. O., 1957, Vermiculite:  Virginia Division of Mineral Resources, Virginia Minerals, v. 3, n. 1, p. 1-6. 

Potter, Michael J., 2003, Vermiculite: U.S. Geological Survey Minerals Yearbook, p. 81.1-81.3.

Virginia Division of Mineral Resources, 1993, Geologic Map of Virginia: Virginia Division of Mineral Resources, scale 1:500,000.