Soapstone is a rock composed mainly of the mineral talc. Popularly the terms _talc_ and _soapstone_ are often used synonymously. The softness, greasy feel, ease of shaping, and resistance to heat and acids of this material make it useful for many purposes. Soapstone is cut into slabs for laundry tubs, laboratory table tops, and other structural purposes. Finer grades are cut into slate pencils and acetylene burners. Ground talc or soapstone is used as a filler for paper, paint, and rubber goods, and in electrical insulation. Fine grades are used for toilet powder. Pyrophyllite (hydrated aluminum silicate) resembles talc in some of its properties and is used in much the same way. Fine English clays (p. 85) are sometimes used interchangeably with talc as paper filler. The United States produces nearly two-thirds of the world's talc. The other large producers are France, Italy, Austria, and Canada (Ontario). The United States is independent of foreign markets for the bulk of its talc consumption, but some carefully prepared talc of high quality is imported from Canada, Italy, and France. Italy is our chief source of talc for pharmaceutical purposes, though recently these needs have been largely supplied by high-grade talc from California. In the United States, Vermont and New York are the leading producers of talc and Virginia of soapstone slabs. Reserves are large. GEOLOGIC FEATURES Talc is hydrated magnesium silicate, as is also serpentine, a mineral with which talc is closely associated. Both are common alteration products of magnesian silicate minerals such as olivine, pyroxene, and amphibole. Talc is also derived from the recrystallization of magnesian carbonates. Talc deposits consist of lenses and bands in metamorphic limestones, schists, and gneisses of ancient age. The talc itself is usually schistose like the wall rocks, and is largely a product of mechanical mashing. In some cases, also, talc results from the alteration of igneous rocks without mashing--as in the case of the large talc and soapstone deposits of Virginia, which are the result of rather complete alteration of basic igneous rocks such as peridotites and pyroxenites.