Strategic minerals are commodities essential to national defense for which the supply during war is wholly, or in part, dependent upon sources outside the boundaries of the U.S. Because these resources would be difficult to obtain, strict measures controlling conservation and distribution are necessary. Critical minerals, on the other hand, although essential to the national defense, are less difficult to procure during wartime because they can either be produced in the U.S. or obtained in adequate quantities from reliable foreign sources. Some conservation of critical minerals may be necessary for nondefense uses. Usually a chronic domestic shortage exists for strategic minerals; potential economic reserves may or may not exist. Potential economic reserves of critical minerals may be relatively abundant, but the U.S. may rely heavily on foreign sources of raw ore simply because of economic, social, environmental, or political reasons.
Historic strategic mineral occurrences in Colorado are discussed in IS-17 Geology and Resource Potential of Strategic Minerals in Colorado. However, the U.S. Geological Survey (USGS) updated the list of critical minerals in 2018 and is developing a strategy to reduce U.S. reliance on these resources. This includes identifying areas that host critical minerals and improving geologic and geophysical mapping in these areas. The CGS is currently working with the USGS to determine priority areas that may contain potential resources of critical minerals in Colorado.
The lists for strategic and/or critical minerals have changed over time. Since the first list in 1941, a number of new minerals have been added. In 1979, 29 critical minerals were listed of which 17 were designated as strategic. A historic analyses of the geology and resource potential of these minerals is provided in the CGS publication IS-17 Geology and Resource Potential of Strategic Minerals in Colorado. However, the USGS in 2018, again updated the list of critical minerals and is developing a strategy to reduce U.S. reliance on critical minerals. This process includes identifying areas that host critical minerals and improving geologic and geophysical mapping in those areas.
The 2018 critical minerals list includes (in alphabetical order): aluminum (bauxite), antimony, arsenic, barite, beryllium, bismuth, cesium, chromium, cobalt, fluorspar, gallium, germanium, graphite (natural), hafnium, helium, indium, lithium, magnesium, manganese, niobium, platinum group metals, potash, the rare earth element (REE) group, rhenium, rubidium, scandium, strontium, tantalum, tellurium, tin, titanium, tungsten, uranium, vanadium, and zirconium. The use of these critical minerals in the U.S. is presented in the USGS critical minerals publication and in their annual U.S. commodity production summaries.
Minerals containing almost all the elements provided in the 2018 critical mineral list occur in Colorado. However, many of these may not occur in sufficient quantities or volume to mine economically. Colorado is a known producer or past producer of several of the critical minerals/mineral materials especially (in no particular order) helium, tungsten, uranium, and vanadium. Also, Colorado contains deposits of titanium, niobium, REE, and potentially lithium, as well as other critical minerals that may be economical to extract.
As a participant in the USGS Earth Mapping Resources Initiative project, the CGS joined in several workshops with USGS representatives to identify areas where critical minerals are likely to occur. The first round of these workshops concentrated on Rare Earth Element (REE) deposits while subsequent meetings have concentrated on the other critical minerals. As a result of these workshops, the CGS is currently creating a compilation geologic map in an area just west of the Wet Mountains. This geologic map will be utilized during a forthcoming high resolution geophysical survey to be conducted by the USGS in this area. The article “Earth MRI Funds Critical Minerals Projects in Colorado” provides more details about this project. In anticipation of this project, the CGS also completed a summary of the geology and compilation of historic REE sampling results from previous studies conducted in this area. The report and data compilation (including the GIS files and spreadsheet) are available as a free download (O’Keeffe and others, 2021).
Several of the critical minerals (e.g. bismuth, gallium, germanium, indium, tellurium, etc.) occur in such small concentrations in U.S. ore deposits that they are uneconomical to mine alone and are recovered as byproducts of mining other minerals such as copper, lead, molybdenum, silver, gold, and zinc. All of these metal commodities were historically mined in Colorado and molybdenum, gold, and silver are still being mined. Future sources of some of these critical minerals may be associated with these precious and base metal deposits and tied to the processing of these other mineral commodities. For example, the Climax Mine, located in Lake and Summit counties, is primarily mined for molybdenum. However, in the past, tungsten was recovered during mining of molybdenum because it was economical and due to its present in ores at the time. The Climax Mine is a Climax-type porphyry mineral deposit along with the Henderson and Urad Mines. Colorado hosts six of the thirteen known mineral deposits of this type. The other three known deposits have been explored and could contain additional molybdenum and critical minerals. There may be more of these undiscovered deposit types in the state.
Deposits of critical minerals in Colorado include niobium, REE, titanium, tungsten, helium, uranium, and vanadium. Both uranium and vanadium were mined in Colorado and several companies maintain mining permits associated with these commodities. Uranium and vanadium resources exist in the Uravan mineral belt in Mesa, Montrose, and San Miguel counties. Other resources for uranium exist in other parts of the state including Park, Fremont, Garfield, Rio Blanco, Moffat, and Weld County. A data set showing the locations of radioactive mineral occurrences in Colorado is available as a download and as an online map.
The Iron Hill-Powderhorn mining district in Gunnison County contains documented niobium, REE, and titanium resources. Other potential resources for REE include an area just west of the Wet Mountains in Fremont and Custer counties. These deposits are alkaline intrusive complexes and are discussed, along with other areas, in RS-35 Alkalic Igneous Rocks of Colorado and Their Associated Ore Deposits. The Department of Energy is evaluating critical minerals including REEs in coal. Colorado has abundant coal resources and future critical mineral evaluations should include coal and associated deposits.
Colorado was a significant producer of tungsten from Boulder County until the 1950s. Tungsten was also produced as a byproduct of molybdenum mining at the Climax Mine (Lake and Summit counties) until 1986. Other potential tungsten resources include the San Juan Mountains in Dolores and San Juan counties.
The state has several areas that may contain helium resources. Helium is currently produced in Cheyenne and Montezuma counties. Other helium resources occur in Garfield, Las Animas, and Dolores counties.
Other potential sources of critical minerals in Colorado include pegmatites and Cretaceous beach placer deposits. Several of critical minerals have been produced in small quantities from pegmatite deposits across the state. The CGS recently conducted a study on a marine beach placer containing REE, titanium, zirconium, and potentially hafnium deposits in Elbert County.
Critical minerals are used in several electronic, manufacturing, military, medical, energy, and aerospace applications. These applications include but not limited to the following:
- aerospace guidance (REEs), aircraft (aluminum, titanium, vanadium), jet engines (chromium, cobalt, rhenium, tantalum, titanium, tungsten, vanadium, zirconium),
- batteries (antimony, manganese), rechargeable batteries (cobalt, graphite. lithium, vanadium), fuel cells (scandium), power transmission lines (aluminum), solar cells (arsenic, gallium, germanium, indium, tellurium),
- body armor (graphite), armor (titanium), military countermeasures (magnesium), targeting systems (beryllium),
- catalysts (PGMs, rhenium, tungsten, vanadium), flame retardants (antimony), fertilizer (potash),
- cell phones (gallium, tantalum, lithium), satellite communications (beryllium), microwave communications (arsenic), fiber optics (germanium, REEs), global positioning satellites (cesium, rubidium), radar (cobalt, beryllium, gallium),
- cutting and drilling tools (tungsten), solders (antimony, bismuth, indium, tin), steel and/or high strength steel (fluorspar, graphite, manganese niobium, vanadium), stainless steel (chromium), super alloys (chromium, cobalt, niobium, PGMs, rhenium, tantalum, titanium, tungsten, vanadium, hafnium), lightweight alloys (aluminum, lithium, magnesium, manganese, scandium, strontium, titanium), other specialty alloys (beryllium, indium, REEs),
- infrared devices (antimony, germanium, tellurium), lasers (REEs), light-emitting diodes (LEDs) (gallium), magnets (cobalt, REEs, strontium), flat-panel displays (indium, tin), phosphors (REEs),
- medical applications (antimony, beryllium, bismuth, cesium, rubidium, helium, uranium), and
- nuclear applications (antimony, beryllium, fluorspar, uranium, zirconium).
U.S. Geological Survey – Focus Areas for Data Acquisition for Potential Domestic Sources of Critical Minerals—Rare Earth Elements — Open-File report on focus areas for REEs in the US.
U.S. Geological Survey – Mineral Commodity Summaries — Commodity summary reports listed by year. The first portion of these annual documents presents the U.S. net import reliance on commodities and where the U.S. imports them from.