U.S. DEPARTMENT OF THE INTERIOR U.S. GEOLOGICAL SURVEY TALC RESOURCES OF THE CONTERMINOUS UNITED STATES By Robert C. Greene J_/ Open-File Report OF 95-586 This report is preliminary and has not been reviewed for conformity with U.S. Geological Survey editorial standards. Any use of trade, product, or firm names is for descriptive purposes only and does not imply endorsement by the U.S. Government. 1995 Menlo Park, CA 94025 Talc Resources of the conterminous United States Contents Abstract ....................................................................................4 Introduction ..............................................................................8 Talc and talc-bearing rocks .........................................................9 Physical, chemical, and optical properties of talc .........................10 Geology and Genesis of Talc Deposits ........................................11 Deposits in sedimentary rocks ..........................................11 Deposits in ultramafic rocks .............................................12 Uses for talc ............................................................................17 Mining and processing ..............................................................18 Environmental considerations ....................................................19 Acknowledgments ....................................................................19 California ...............................................................................20 Nevada ...................................................................................39 Oregon ...................................................................................41 Washington .............................................................................48 Idaho ......................................................................................52 Montana .................................................................................53 Wyoming ...............................................................................57 New Mexico ...........................................................................60 Texas .....................................................................................61 Arkansas ................................................................................66 Southern and central Appalachian Mountains, Introduction .........68 Alabama ................................................................................69 Georgia .................................................................................71 South Carolina .......................................................................77 North Carolina ......................................................................80 Virginia ................................................................................87 District of Columbia ...............................................................96 Maryland ...............................................................................96 Pennsylvania ......................................................................... 99 New Jersey ...........................................................................101 Appalachian Mountains in New England, Introduction ..............102 Connecticut ..........................................................................104 Rhode Island ........................................................................105 Massachusetts .......................................................................106 Vermont ..............................................................................110 New Hampshire ....................................................................122 Maine ..................................................................................123 New York ............................................................................125 Wisconsin .............................................................................128 References ............................................................................142 Plate 1. Talc map of the United States, exclusive of Alaska and Hawaii Figures 1. Sketch cross-sections of typical "Vermont type" talc deposits, based on Waterbury and Barnes Hill localities (Chidester, 1962) ......14, 15 2. Geologic sketch map of the Klamath Mountains in California, showing the locations of talc occurrences .......................................22, 23 3. Geologic sketch map of the northern and central Sierra Nevada foothills metamorphic belt, California, showing the locations of talc occurrences ................................................................................26, 27 4. Geologic sketch map of the southern part of the Sierra Nevada foothills metamorphic belt and plutonic belt, California, showing the locations of talc occurrences ........................................................28, 29 5. Geologic sketch map of the Inyo-Panamint talc district, California .........................32,33 6. Geologic sketch map of the southern Death Valley-Kingston Range talc district, California ......................................................36, 37 7. Geologic sketch map of the Klamath Mountains in Oregon, showing the locations of talc occurrences ......................................42, 43 8. Geologic sketch map of parts of the Aldrich and Blue Mountains in Oregon, showing the locations of talc occurrences ......................46, 47 9. Simplified geologic map of the Ruby Mountains talc district, Montana .....................................................................................54, 55 10. Simplified geologic map of the Allamoore talc district, Texas .........................62,63 11. Geologic map of the Chatsworth talc district, Georgia .....74, 75 ultramafic rocks. Talc is very soft and is a standard in the Mohs scale, with a hardness of 1. Ground talc is a commercial product which commonly contains impurities of other minerals, including amphiboles, micas, serpentine, and carbonates. Soapstone and steatite are other common names for talc- bearing rocks. Many of the most productive deposits of talc are formed by the metasomatic introduction of silica into carbonate rocks. Silica is mostly derived from adjacent siliceous sedimentary rocks. Important gangue minerals formed during metasomatism include chlorite, Fe oxides, tremolite, serpentine, diopside, and forsterite. Intrusive magmas locally appear to be heat and solution sources; elsewhere, evidence for their presence is lacking. Other deposits are derived from ultramafic rocks. These rocks are commonly, at least in part, converted to serpentinite during their emplacement as ophiolite fragments or during cooling as intrusive rocks. Later, low-temperature hydrothermal solutions have steatized part or all of the serpentinite bodies, producing either a body having zones of talc- carbonate, pure talc, and chlorite blackwall or a soapstone containing talc, chlorite, actinolite, serpentine, carbonate, and Fe-oxide minerals. Ground talc is widely used in ceramics, paint, paper, plastics, and roofing. Other uses include textiles, rubber, lubricants, and cosmetics. Dimension-stone talc is used for building stone, stoves, carvings, and other products. Talc is extracted from both open-pit and underground mines. Some is dry-ground, other material undergoes complex beneficiation to produce a pure finely-ground product. There are few environmental problems of a chemical nature associated with talc mining, but dust mitigation is a necessity. Important talc mining districts, including both recent producers and historically important ones, are located in California, Nevada, Washington, Montana, Texas, Arkansas, Alabama, Georgia, North Carolina, Virginia, Maryland, Pennsylvania, Massachusetts, Vermont, and New York. Districts in California include two important producers, the Inyo- Panamint and the Southern Death Valley-Kingston Range. In the former district, hydrothermal replacement of Ordovician and Silurian carbonate rocks and quartzite has produced deposits of exceptionally pure talc. In the latter district, Proterozoic carbonate rocks have been replaced by talc and tremolite with the aid of solutions formed by connate water heated by adjacent diabase sills. The Palmetto and Sylvania districts in westernmost Nevada have produced talc from carbonate and clastic rocks of Late Proterozoic and Early Cambrian age. Low-temperature hydrothermal solutions possibly derived from Jurassic plutonic rocks have formed talc and chlorite. Districts in Washington near Mount Vernon and Marblemont, as well as an area west of Waterville, have all produced talc. Deposits are in blocks of serpentinized ultramafic rocks, metamorphosed at various times in the Mesozoic and Tertiary. The Dillon-Ennis district in Montana features talc deposits in Archean marbles interlayered with gneiss, quartzite, and other metamorphic rocks. Granulite facies metamorphism was followed by retrograding and replacement of dolomite and silicate minerals by talc. The Allamoore district in western Texas has talc deposits in phyllite, cherry limestone, and dolomite of Precambrian age. Hydrothermal alteration of these rocks has produced a dark talc very low in Fe. A talc district west of Little Rock, Arkansas is in Ordovician rocks of the Ouachita fold and thrust belt. Talc deposits are in zoned lenticular serpentinite bodies. Talc deposits in the Winterboro district, Alabama are in the Shady Dolomite of Cambrian age. Hydrothermal solutions of unknown origin have replaced