Mining has long been part of Wisconsin’s economy and history and even precedes our statehood. On this page, you will find information about two types of mining in Wisconsin: iron mining and frac sand mining. There are also links to additional information about mining in Wisconsin at the bottom of this page.
Types of iron ore
Iron ore is present in a number of places and geologic settings within Wisconsin. Iron ore can be defined on the basis of its iron content into low-grade ore (taconite), which commonly contains 25 to 35% iron, and high-grade ore, which contains 50 to 70% iron.
Iron-bearing ore minerals include oxides, carbonates, silicates, and, in some cases, sulfides. In Wisconsin, the most important iron ore minerals are oxides: magnetite (Fe3O4), hematite (Fe2O3), and goethite/limonite (Fe2O3•H2O).
Brief overview of Wisconsin’s iron mining history
Limited amounts of high-grade iron ore were first mined in Wisconsin in the 1850s in the Black River Falls District of Jackson County and the Ironton area of Sauk County. More substantial iron mining of high-grade ore began in the Gogebic and Florence Districts in the 1880s and continued into the 1960s. Mining in the Baraboo District took place between 1904 and 1925. The Jackson County Iron Company re-opened mining in the Black River Falls District in 1969 when they began extracting low-grade taconite ore that was beneficiated (concentrated) and pelletized on site. The mine ceased operations in 1983 and was reclaimed.
Significant remaining tonnages of lower-grade ore have been identified by magnetic surveys and limited core drilling in several of the aforementioned districts, most notably the Gogebic District in Iron and Ashland counties. Future development will depend on economic and environmental considerations.
For more information
For more details about iron mining in Wisconsin, please contact:
Esther K. Stewart
phone: (608) 263-3201
Background on metallic mining regulations and resources
- Overview of metallic mineral regulation in Wisconsin, third edition (Special Report 13), 2004, Thomas J. Evans
- Mineral and water resources of Wisconsin, 1976, prepared by the US Geological Survey in collaboration with the Wisconsin Geological and Natural History Survey
- Iron mining in Wisconsin, 2011, Wisconsin Geological and Natural History Survey Factsheet 3. (Formatted version of the map and text on this page.)
- Metallic mineral deposits, 2014, Wisconsin Geological and Natural History Survey Factsheet 4.
- Mining information sheets, prepared by the Wisconsin Department of Natural Resources to explain metallic mining regulations in Wisconsin. (Includes information about the permitting process, how the DNR regulates metallic mining, local decisions, and reclamation issues and requirements.)
What is frac sand?
Frac sand is quartz sand of a specific grain size and shape that is suspended in fluid and injected into oil and gas wells under very high pressure. The fluid pressure opens and enlarges fractures as well as creates new ones. Sand grains are carried into these fractures and prop them open after the fluid is pumped out.
The type of sand used in this process must be nearly pure quartz, very well rounded, extremely hard, and of uniform size. Before shipment, frac sand is washed, sorted to ensure uniformity, and dried.
Wisconsin has some of the best frac sand in the country because several of our geologic formations meet these specifications and are found near the surface.
Where is frac sand found?
Frac sand is currently being mined from sandstone formations in much of western and central Wisconsin. The same formations are less well exposed and generally more fine-grained in the eastern and southern parts of the state. Sand from younger glacial deposits as well as most beach and riverbank sand is too impure and too angular to be used as frac sand.
Where is fracking performed?
Fracking has been used by our domestic oil and gas industry for more than 75 years. In recent years, the development of new horizontal drilling technology using hydraulic fracturing has made possible the production of previously unrecoverable natural gas resources in the eastern, western, and southwestern United States.
In Wisconsin, a different kind of fracking is used to increase the productivity of water supply wells in relatively impermeable rocks, such as the granite in the central part of the state. In these cases, only pressurized water is injected into the well—no sand is added.
Permits and regulations
Concerns have been raised regarding environmental and nuisance problems as sand mines proliferate. Mine siting is regulated at the local zoning level. Mine reclamation plans, required by NR 135, must be in place before mining begins. The Department of Natural Resources provides technical assistance to local authorities for these plans. For a summary of Wisconsin’s nonmetallic mining regulations, visit the DNR website.
For more information
Contact the following staff at the Wisconsin Geological and Natural History Survey for more details about frac sand in Wisconsin:
phone: (608) 262-9403
Mine locations map: Wisconsin Department of Natural Resources—Industrial Sand Mining
Interactive map shows locations and types of frac sand mining operations
- Wisconsin Center for Investigative Journalism: Covers a variety of topics about frac sand mining
- Wisconsin Department of Natural Resources—Silica Sand Mining Report: Overview of the industry and potential impacts (PDF)
- U.S. Geological Survey: Frac Sand in the United States—A Geological and Industry Overview: Description of frac sand deposits and locations, and estimates of production, consumption, and reserves. A companion map shows locations of frac sand sources across the United States.
Economics: The Federal Reserve Bank of Minneapolis—Regional Business & Economics Newspaper
Article outlines the economic evaluation of frac sand mining (PDF)
Mining statistics: U.S. Geological Survey—Silica Statistics
Annual reports for national silica mining statistics
Planning and zoning: Center for Land Use Education (UW–Stevens Point)—Mining Publications and Resources
Four-part series on planning, zoning, and evaluating county nonmetallic mining plans
- Wisconsin Department of Natural Resources—Industrial Sand Mining: Information on WDNR regulations, air monitoring, silica sand, and rules governing reclamation
- Wisconsin Legislative Council—Information Memorandum: 10-page report detailing types of ordinances that a local government may enact to regulate sand mining plus examples of state and federal permits that might be required for certain environmental impacts (PDF)
Silica dust: Occupational Safety and Health Administration—Crystalline Silica
Occupational health hazards and symptoms of exposure to silica dust