Assessing Mineral Resources in the WLCI Region
Photo of trona, or soda ash, processing facility.

Southwest Wyoming is rich in mineral resources, including the world’s largest deposit of trona, which is the state’s top mineral export. Trona is mined underground and then processed to make soda ash, or bicarbonate of soda, that is used in the manufacture of many products, including glass, detergents and cleaning agents, and even food additives.

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Central Mineral and Environmental Resources Science Center


Why Is Identifying Mining Operations and Mineral Deposits Important to the WLCI?

Southwest Wyoming is rich in mineral resources, notably trona, uranium and phosphate. Base and precious mineral deposits are also found here. Mining products are among the top exports for the state of Wyoming and vital components of the economy. Mining activities and supporting infrastructure, however, can affect wildlife and ecosystems through habitat loss, water quality degradation, and contamination of soil and water with toxic metals. Understanding the extent of mineralization and historic mining activity allows us to predict the likelihood of continued or future mining development and its associated effects. Planners and decisionmakers can use this information to direct development to benefit all stakeholders as well as providing for sustainable wildlife habitat and water quality. There was a lack of up-to-date information on mineral resources in the WLCI region at the beginning of the WLCI. Geologists from the USGS Central Mineral and Environmental Resources Center conducted an assessment of mineral resources in the WLCI region. This information is being used to create maps and predictive models for use in planning resource extraction while reducing risk to wildlife and water quality.

Study Objectives

To understand the current extent of mineralization and mining activity (excluding coal and other energy minerals, with the exception of uranium), and the likelihood of continued or future mining development in the WLCI region.

  • Provide an overview of known mineralized areas in WLCI
  • Update resources database with the status and location of historic mines and prospects in WLCI
  • Catalog current mine workings
  • Revise the USGS Mineral Resources Data System (MRDS) based on current information
  • Track the changes of claimed lands over time
  • Develop an understanding of why the deposits occur where they do
  • Extrapolate potential for mineralization to areas that could be of economic interest in the future
Map of mineralized areas and mineral deposits in the WLCI region

Locations of mineralized areas (lines) and deposits (symbols) in and immediately adjacent to the WLCI study area. Base- and precious-metals are shown in red, uranium in yellow, trona in pink, phosphate in blue. Click to enlarge.

Mapping Mineralized Areas

Numerous mineral deposits are located within the WLCI area, mostly within 19 mineralized areas. Remnants of historic copper, lead, zinc, silver, gold, and other metal mines are preserved in these districts. Although Wyoming has had a rich mining history, with a few notable exceptions, currently the industry is mostly dormant in the WLCI study area. Based on information from historic maps, the geologic literature, and the USGS Mineral Resources Data System, locations of the known mines, prospects, and occurrences were plotted on geologic and topographic maps with GIS software. From these maps, mineralized areas were identified based on clusters of similar mineral deposit types within similar geologic settings. Within each of the mineralized areas, attempts were made to visit the mines, prospects, or occurrences listed in the database. Each site visited was compared with historic records or to references of it in the literature and(or) on maps. The records of these sites in the USGS database were revised as needed. The local geology, extent of mining disturbance or activity (if any), and any ore minerals or commodities present were noted.

Photo of USGS geologist documenting observations at abandoned mine site.

USGS geologists visited locations of old mines in the WLCI region and documented their location, extent, and current activity.

Remnants of historic copper, lead, zinc, silver, gold, and other metal mines are found throughout southwest Wyoming.

Many former phosphate mines dot the WLCI region, but none are currently active. Some of the largest, such as South Mountain (above), have been reclaimed. Reclamation can mitigate the effects of previous mining activities and restore wildlife habitat.