Industrial Minerals of the United States U.S. Talc—Baby Powder and Much More When most people think of talc, Geology of U.S. Talc Deposits The majority of the large U.S. talc they probably envision talcum and deposits are those that replaced metamorphosed dolomite. Other baby powder. Since talc is very soft Significant United States talc large deposits of this general type are and easily carved, one might also deposits occur in the Appalachians in St. Lawrence County, N.Y., the think of sculptures in soapstone and Piedmont, from Vermont to Murphy Marble Belt of North (massive talc). In fact, these uses of Alabama, and in the West in Carolina, and in the Inyo and talc are quite minor compared to its Montana, California, Nevada, wide variety of applications in Panamint Ranges of California Washington, Idaho, and New Mexico. (Chidester and others, 1964; manufacturing and agriculture. (See Chidester and others, 1964.) High-quality (pure) talc has many Piniazkiewicz and others, 1994). In Large deposits also occur in Texas, contrast, the Winterboro deposits in physical and chemical properties but economic deposits are otherwise favorable for its use, such as its Talladega County, Ala., occur in lacking between the Appalachians dolomites that appear relatively softness, purity, fragrance retention, and the Rocky Mountains. whiteness, luster, moisture content, unmetamorphosed. The talc deposits Talc is formed by two processes. In of the Chatsworth district of Georgia oil and grease adsorption, chemical the first process, heated waters inertness, low electrical conductivity, and the Allamorre district of Texas carrying magnesium and silica in formed in metamorphic rock with high dielectric strength, and high solution react with and replace beds much more quartz than the dolomite- thermal conductivity (Virta, 1998). of dolomitic marble. Examples are hosted deposits just noted. the large talc deposits of southwestern The second process for forming talc What is Talc? Montana that formed by the involves the alteration of igneous replacement of marble. This talc may rocks that contain abundant, heavy Talc is a hydrous silicate mineral have formed more than 1 billion years minerals called "mafic," which are composed of magnesium (Mg), ago. In these deposits, the marble enriched in magnesium and iron. A containing the talc is metamorphic sequence of fluids reacts with the silicon and oxygen (SiO2, silica), and water. Its chemical formula is rock formed from dolomite that magnesium-rich mafic minerals in the changed form (metamorphosed) host rocks, ultimately replacing the Mg3Si4O10(OH)2. Talc is relatively pure in composition but can contain under heat and pressure. It is not mafic minerals with talc. These talc deposits form as rinds on the mafic small amounts of aluminum, iron, known with certainty if this igneous rock bodies or nearly manganese, and titanium. Talc can metamorphism or another deep heat completely replace them; they are be white, apple green, dark green, or source was responsible for heating the typically tabular or lenticular talc brown, depending on its waters that created the extensive talc bodies that can reach 100 m in composition. deposits in Montana. The replace­ thickness and extend more than 300 Talc is the softest mineral, having ment talc deposits range from pods centimeters thick to the 29-m-thick m in length. Large deposits of this a Mohs hardness of 1, compared to type are mined in Vermont, and diamond with a hardness of 10. It is talc body at the Treasure Chest mine near Dillon, Mont. (See Berg, 1979.) smaller deposits have been mined in composed of microscopic platelets, the eastern States, California, and and the bonds holding the platelets Texas. (See Chidester and others, together are very weak. This enables 1964; Piniazkiewicz and others, the platelets to slide by one another 1994.) These deposits have been and results in the soft and greasy feel important sources of darker talc, of talc. commonly referred to as soapstone, Talc is also used as a term to owing their coloration to impurities. describe a rock that contains the Thus, the host rock and process of mineral talc. Other names for talc- formation determine the qualities of rich rocks are steatite, a high-purity talc, which in turn affect the industrial massive variety, and soapstone, an applications of a particular deposit. impure rock containing talc and The grain size and shape, color, and other minerals. purity of talc influence its uses. Processing Talc

Conventional open pit mining techniques are used to produce almost all the talc mined in the U.S. Typically, the ore is drilled, blasted, and partially crushed at the mine. Selective mining and (or) hand or machine sorting may be used to produce high-grade ore feed for the mill. At the mill, the ore is further crushed and finely ground. In some instances, flotation processes are used to remove mineral impurities. Most companies produce dozens of Talc, soapstone, and steatite were References Cited talc products that differ primarily in excavated from 13 mines in six particle size, particle size States in 1999. Only one of these Berg, R.B., 1979, Talc and chlorite distribution, brightness, mineral talc mines was an underground deposits in Montana: Montana composition, and bulk density. operation; the other 12 were surface Bureau of Mines and Geology mines. Montana led the U.S. in Memoir 45, 66 p., 3 plates. 1999 talc production, followed by Chidester, A.H., Engel, A.E.J., and Talc's Many Uses Texas, Vermont, New York, Oregon, Wright, L.A., 1964, Talc resources of and California. the United States: U.S. Geological U.S. talc is used in the production Montana has been the leading talc- Survey Bulletin 1167, 61 p., 7 plates. of ceramics (the main domestic producing State in the U.S. for more Piniazkiewicz, R.J., McCarthy, E.F., and Genco, N.A., 1994, Talc, in Carr, use), paint, paper (for improving than 20 years, supplying more than D.D., ed., Industrial minerals and several paper qualities and in one-third of the U.S. production in recycling processes), plastics (as a rocks, 6th Edition: Littleton, Colo., recent years. All production has Society of Mining, Metallurgy, and functional filler, providing rigidity come from large deposits of high- Exploration, Inc., p. 1049–1069. to the plastic), roofing, rubber, purity talc in the southwestern part Virta, R.L., 1998, Talc and pyrophyllite, cosmetics, flooring, caulking, and of the State. The largest producer in in Minerals yearbook, metals and agricultural applications. As Montana, and the U.S., is the minerals 1996, vol. I: U.S. examples, talc is used in the Yellowstone mine, an extensive open Geological Survey, p. 891–897. ceramic substrate of catalytic pit operation near Ennis, Mont. convertors, and is found in wire and During the late 1990's, the cable insulation, auto body putty, Yellowstone mine produced about Information asphalt shingles, caulks, sealants, 300,000 short tons (270,000 metric joint compounds, foam packaging, tons) of crude talc ore per year For more on the U.S. talc industry contact: animal feed, pharmaceuticals, (Montana Bureau of Mines and Robert L. Virta chewing gum, candy, gaskets, Geology annual reports). U.S. Geological Survey hoses, belts, flooring (providing Domestic development and Reston, VA softness and flexibility), insecticide exploration for talc are expected to (703) 648-7726 carriers, and of course, baby and stay relatively steady in the [email protected] body powders. Thus, talc is a part foreseeable future because: For more on U.S. talc geology contact: of everyday life. demand for domestic talc is expected to continue based on Bradley S. Van Gosen U.S. Geological Survey recent market trends (Virta, The U.S. Talc Industry Denver, CO 1998); (303) 236-1566 large mines are active and an [email protected] The U.S. is second only to infrastructure for talc processing Richard B. Berg People's Republic of China in is in place; Montana Bureau of Mines and Geology annual talc production, with U.S. no significant acid mine drainage Butte, MT mines producing around 1 million is associated with talc mining. (406) 496-4172 [email protected] metric tons of crude talc ore per However, the presence of long, year during the 1990's (Virta, thin amphibole minerals within 1998). Production of talc is an some talc deposits has received approximately $100 million per much public scrutiny as a health Any use of trade, product, or firm names is for descriptive purposes only and does year industry in the U.S. issue. not imply endorsement by the U.S. Government.