Bentonite and fuller's earth resources of the United States

Abstract

The term bentonite is defined as any natural material composed dominantly of the clay minerals of the smectite group and whose properties are controlled by these clay minerals. Fuller's earth refers to naturally occurring material that has a high absorptive capacity. Both bentonite and fuller's earth have a wide variety of physical properties that make them suitable for many commercial uses and applications. The sodium or Wyoming bentonite is a high swelling variety used in drilling muds, bonding foundry sand, and pelletizing taconite iron ores. The calcium or southern bentonite is a low or nonswelling variety used for bonding foundry sand where a highstrength green bond is required. Large amounts of fuller's earth are utilized to make granules that are used as an absorbent for oils, grease, chemicals, as an animal litter, and as a soil conditioner. Almost all of the commercial deposits of bentonite and fuller's earth are in geologic formations that are either Cretaceous or Tertiary in age. Bentonite occurs in Tertiary rocks in the Atlantic Coastal Plain, the Gulf of Mexico Coastal Plain, and in the Mississippi embayment. The best grade swelling bentonite occurs in the Mowry Shale of Cretaceous age in Wyoming and Montana. The most abundant nonswelling bentonite is found in Tertiary formations of the Jackson and Claiborne Groups in Texas. An important geologic unit for fuller's earth deposits is the Tertiary Hawthorn Formation of Georgia and Florida. In 1988, almost 75 percent of the bentonite production in the United States came from Wyoming. Alabama and Mississippi together produced about 14 percent; California produced about 4 percent, and Arizona, Texas, and Utah each produced about 1 percent. States producing less than 1 percent of the U.S. bentonite were Colorado, Idaho, Kansas, Montana, Nevada, Oregon, and Tennessee. In 1988, almost 50 percent of the fuller's earth produced in the United States came from Georgia and Florida. Other States producing fuller's earth were Illinois, Mississippi, Missouri, Nevada, South Carolina, Tennessee, Texas, and Virginia.