Kyanite

Kyanite is an aluminosilicate mineral and member of the sillimanite group (kyanite, sillimanite, andalusite), which all have the same chemical formula, Al₂SiO₅.  Because it is physically stable at high temperatures, kyanite has many industrial applications.  It is used primarily as an additive in the production of high-temperature ceramic products such as furnace bricks, but is also used in abrasives, brake shoes, cookware, and a wide variety of other industrial and consumer products.   The major consumers of kyanite are the steel and aluminum industries.

Kyanite Mining Corporation, located in Buckingham County, is the only producer of kyanite in North America and the largest producer in the world.  The company operates two open pit mines a mile apart, one at Willis Mountain and one at East Ridge.  The ore bodies are part of a kyanite quartzite zone within the Chopawamsic Formation, which is a sequence of metavolcanic and metasedimentary rocks of Ordovician age.  Willis Mountain and East Ridge are on the west and east limbs, respectively, of the Whispering Creek anticline. 

The company’s processing facilities include jaw crushers, rod and ball mills, spiral, magnetic and froth floatation separators and calcining kilns.  Some of the kyanite is calcined to produce mullite, which is even more thermally stable than kyanite.  Mullite results from the irreversible expansion of kyanite at about 3000 degrees F.

Annual production figures for processed kyanite and mullite are not available. The U.S. Geological Survey estimates that production has remained fairly stable, at about 90,000 tons per year for kyanite and 40,000 tons per year for mullite.  Domestic consumption is closely tied to the steel industry, which has been in general decline in recent years. 

One of Kyanite Mining Corporation’s processing facilities at Willis Mountain,
Buckingham County.

Selected References:

Conley, J. F., and Marr, J. D., 1980, Evidence for the correlation of the kyanite quartzites of Willis and Woods mountains with the Arvonia Formation:  Virginia Division of Mineral Resources Publication 27, p. 1-11.

Dixon, G. B., Jr., 1980, Kyanite mining in Virginia:  Virginia Division of Mineral Resources, Virginia Minerals, v. 26, n. 1, p. 12.

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.

Johnson, S. S., 1967, Virginia’s contribution to the kyanite – mullite industry:  Virginia Division of Mineral Resources, Virginia Minerals, v. 13, n. 1, p. 1-7.

Jonas, A. I., and Watkins, J. H., 1932, Kyanite in Virginia, (Including) Geology of the kyanite belt of Virginia:  Virginia Division of Mineral Resources Bulletin 38, 52 p.

Marr, J. D., 1990, Geology of the Kyanite Deposits at Willis Mountain, Virginia, in Proceedings 26th Forum on the Geology of Industrial Minerals:  Virginia Division of Mineral Resources Publication 119, p. 129-134.

Potter, Michael J., 2003, Kyanite and Related Materials: U.S. Geological Survey Mineral Yearbook, p. 42.1-42.2.

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