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Clays
Statistical Compendium


This publication includes data through 1990.
For recent statistics, please go the the Clays Statistics and Information page.

By Robert L. Virta

Clay is a natural, earthy, fine-grained material composed largely of a group of crystalline minerals known as the clay minerals. These minerals are hydrous silicates composed mainly of silica, alumina, and water. Several of these minerals also contain appreciable quantities of iron, alkalies, and alkaline earth.

Clays are bulk commodities that support a variety of substantial industries that are vital in local and regional economies and are important to the national economy. Deposits of common clays, shales, and fire clays are widespread. Ball clay, bentonite, fuller's earth, and kaolin deposits occur in smaller geographic areas.

U.S. production of clays in 1989 was 42 million metric tons valued at $1.5 billion, from 44 States and Puerto Rico. U.S. clay demand during the last two decades has declined because of decreased construction. Large declines in the manufacture of brick, lightweight aggregates, and portland cement were observed during the period. The specialty clays used in more diversified applications and industries fared better. Demand for these clays-- kaolin, ball clay, fuller's earth, and bentonite--has held up well despite some softening in the latter part of the decade.

The forecast range for U.S. clay demand for the year 2000 is between 47 and 77 million metric tons. Probable U.S. demand for 2000 was put at 63 million metric tons. The United States possesses the best overall supply of clays of any country in the world with respect to types as well as quantity. In addition, the United States is more advanced in clay-processing technology than most other countries and is capable of processing clay to meet all domestic consumer requirements.

For several of the clay types, demand and industry employment are strongly influenced by production costs and price. Efficiencies and innovations that would reduce extraction costs would be particularly effective in increasing demand.

Although clays have been used for thousands of years, understanding of the molecular and atomic structure along with tools for measuring and observing the chemical and physical properties of the many clay minerals have only recently been made available and are continually being improved. This type of research is a relatively new field that, if pursued diligently, holds potential for improvements in quality, new physical properties, and even designed physical properties of clays.

Byproducts and coproducts have been given little attention by clay producers. High-quality silica sand is the only significant coproduct. Although the potential for additional coproducts is probably limited by marketing problems, possibilities exist for recovering mica, titanium minerals, and silica from kaolin mining operations.

Most clays are produced from open pits, and the industry is particularly susceptible to land use conflicts. Zoning regulations, waste disposal, and pollution factors will affect the economics of production in a growing number of instances. Devising practices to minimize such conflict demands immediate and concerted attention. Of even more importance is the need for adequate data on clay resources, location of deposits, types of clay, use potential, and tonnage so planners can more intelligently design for the use of land within their purview.


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