Many of the historical metal mining districts in Colorado were created during the initial gold rush of 1858-61 which lead to the discovery of other metals. For example, as summarized from RS-42 Geology and Mineral Resources of Lake County, Colorado, when the gold rush expanded throughout Colorado, mining in the Leadville District began with the discovery of placer gold in California Gulch in the early 1860s. The peak of placer mining lasted from about 1860 to 1863 and declined through 1875. During the mining of placer gold, heavy blue-black sands, recognized by some as lead carbonate, caused issues with the placer mining. Some of this lead carbonate contained silver however, the economics of the day made it difficult to ship this ore to far away smelters unless it contained an abundance of silver. As other deposits in the area were discovered around 1876, some with much higher concentrations of silver, closer new smelters including the lead-silver smelter at Georgetown were being constructed. In 1877, the ore deposits at Fryer Hill near Leadville were discovered, and the silver boom, considered one of the largest in the state, was on. Within two years, the population in Leadville went from 200 people in 1877 to a population of more than 15,000. In 1880, annual production increased to over 10 million ounces of silver and 66 million pounds of lead.
At various times throughout its history, Colorado has been the leading U.S. producer of gold, silver, molybdenum, lead, zinc, uranium, and tungsten. Other metals that have been mined in Colorado include copper, tin, vanadium, iron, beryllium, lithium, thorium, tantalum, and manganese. Many of the ore bodies that were initially mined for one commodity included other valuable base metals. As reported in RS-42, Leadville is one of the great metal producing districts of the world and contains six types of mineral deposit systems. Through 1999, Leadville produced ~28.9 million tons of ore containing 3.3 million ounces of gold, 265 million ounces of silver, 2,354 pounds of lead, 1,936 million pounds of zinc, and 110 million pounds of copper.
Currently, as of 2020, metals mined in Colorado include gold, molybdenum, and silver. Molybdenum is primarily used to produce engineering steels (e.g. superalloys, nickel alloys, and tool steels), stainless steel, molybdenum metal and other alloys, catalysts, pigments, corrosion inhibitors, smoke suppressants, lubricants, and chemicals. In Colorado, molybdenum is mined at the Climax and Henderson mines. A majority of the 2018 primary molybdenum production in the U.S. was from these two Colorado mines that produced approximately 35 million pounds combined. In the U.S., Colorado ranked second in molybdenum production following that recovered as a byproduct of copper mining at several Arizona mines.
The largest producer of gold in Colorado is the Cripple Creek and Victor (CC&V) open pit mine located in Teller County. In 2018, Colorado was the third state in the U.S. for gold production with 360,000 ounces produced from CC&V. Smaller amounts of placer gold is recovered from sand and gravel aggregate operations along some rivers and streams including the South Platte, Arkansas, and Colorado Rivers, as well as Clear Creek. Additionally, a few small lode gold mines operated by private individuals or small groups likely produce small tonnages of high-grade gold and silver ore.
Currently, the majority of metals mined in Colorado include gold, molybdenum, and minor amounts of silver that are recovered during gold mining. Colorado has historically produced gold, silver, molybdenum, zinc, copper, lead, and other metals. Some of these metals are discussed below. Metal occurrences and historic metal mines are common in Colorado. The CGS publication MS-28 Location Map and Descriptions of Metal Occurrences in Colorado with Notes on Economic Potential provides descriptions of metal occurrences and a map showing the general location of these deposits in Colorado. More about historic metal mining by mining district is reported in ON-007-08 Historic Metal Mining Districts of Colorado that includes a data download and an online map. These publications give a summary of the historic mining activities as well as a list of references about the geology of each district or area.
Gold deposit locations and types in Colorado are widespread and diverse. The CGS publication RS-28 Gold Occurrences of Colorado provides a database of gold occurrences, a map showing the locations, and a geologic summary of each deposit type in Colorado. Also, the CGS RockTalk: Gold in Colorado provides an excellent summary of gold in Colorado. The largest gold mining area in the state in terms of production is the Cripple Creek mining district located in Teller County. This area is still being mined today with 2019 gold production from the Cripple Creek and Victor Mine (CC&V) at ~322,000 ounces. Historically producing gold districts in Colorado that once produced over ~1 million troy ounces of gold include the Cripple Creek district in Teller County, Central City district in Gilpin County, Telluride district in San Miguel County, Leadville district in Lake County, Sneffels district in Ouray County, Silverton district in San Juan County, and Breckenridge district in Summit County. Other important mining districts in the state that historically produced over ~500,000 troy ounces of gold include the Idaho Springs district in Clear Creek county, Summitville district in Rio Grande County, and Empire district in Clear Creek County. The Gilman district in Eagle County also produced ~400,000 troy ounces of gold primarily as a byproduct of zinc mining.
Molybdenum is found in many areas of the state, occurring as the sulfide mineral, molybdenite. As discussed in MS-28 Location Map and Descriptions of Metal Occurrences in Colorado, molybdenite was recognized as an ore of molybdenum early on in the state’s mining history but the commodity did not become important until World War I. At that time, in 1917, the world-class Climax deposit located on Fremont Pass, Lake and Summit counties, was brought on line. Climax is one of the largest, if not the largest, known deposits of primary molybdenum ore in the world. At its height of production during World War II, Climax supplied 80 percent of the world’s demand for this steel hardening alloy metal. The CGS RockTalk: Molybdenum in Colorado provides an excellent summary about the history and geology of molybdenum in Colorado.
Today, the Climax and Henderson mine in Colorado are primarily molybdenum mines. In 2019, the Climax and Henderson mines produced 12 and 17 million pounds of molybdenum, respectively. These deposits are complex and are known as Climax-type porphyry molybdenum deposits. Climax-type porphyry deposits are only currently known in western North America. Of the thirteen known deposits of this type, six occur in Colorado and are known as the Climax, Henderson, Mt. Emmons, Silver Creek, Urad, and Redwell Basin deposits. Other metals may be associated with these deposits. Fox example, the Climax Mine historically produced tungsten as a byproduct of molybdenum mining and was the leading tungsten producer in the U.S. for several years.
Silver, Lead, Zinc, and Copper
Several mining districts in Colorado produced gold and silver as well as the base metals (common metals not considered precious) lead, zinc, and copper. Currently, silver is produced as a byproduct of gold mining at CC&V. Some of the larger mining districts associated with silver and base metals, as well as gold, include Leadville, Gilman, Kokomo, and Aspen. Total production from these four districts is estimated as follows: ~502 million ounces of silver, ~1.8 million short tons of zinc, ~1.7 million short tons of lead, ~160,000 short tons of copper, and ~3.6 million ounces of gold. About half of the gold and silver production was from Leadville with most of the gold being produced from the placer deposits in California Gulch (Thompson, 2017).
Through 1999, the Leadville district in Lake County has produced ~28.9 million tons of ore with about 3.3 million ounces of gold, 265 million ounces of silver, 1.18 million short tons of lead, 968,000 short tons of zinc, and 55,000 short tons of copper. The Gilman district, which includes the historic Eagle Mine in Eagle County, produced several metals. Between 1880 and 1972, over 99% of Eagle County production came from the Gilman district including: ~858,000 short tons of zinc, ~148,000 short tons of lead, ~105,000 short tons of copper, ~66 million ounces of silver, and ~393,000 ounces of gold. Up until about 1952, the Aspen district produced about 111 million ounces of silver, 294,000 short tons of lead, and 11,000 short tons of zinc.
Other minerals that have been mined in the past or show some promise in Colorado include barite, beryllium, bismuth, lithium, manganese, niobium-tantalum, REEs, tin, titanium, tungsten, uranium, and vanadium. Some of these materials were produced in greater quantities in Colorado than others including uranium, vanadium, and tungsten. For example, the Uravan mineral belt located in western Colorado has produced large quantities of uranium and vanadium. This area accounted for about 77% of the total uranium production in the state. The Uravan mineral belt produced almost 14 million tons of ore averaging 0.24 percent triuranium octoxide (U3O8) and over 356 million pounds of vanadium oxide. The Schwartzwalder Mine located in Jefferson County was largest single uranium mine in Colorado and produced 10.5 million pounds of U3O8 by 1978.
In the past, Boulder County produced tungsten from areas near Nederland and Ward. The Boulder County mining district produced small quantities up until the late 1950s with most of the ore from the district being produced from the early 1900s to 1918 followed by declining production thru the 1950s. Tungsten was last produced in 1986 as a byproduct of molybdenum mining at the Climax Mine in Lake County.
MS-28 Location Map and Descriptions of Metal Occurrences in Colorado with Notes on Economic Potential — Provides descriptions of metal occurrences and a map showing the general location of these deposits.
RS-28 Gold Occurrences of Colorado — Provides a listing of gold occurrences in the state, a location map, and a geologic summary of the types of gold deposits.
ON-007-08D Historic Metal Mining Districts of Colorado — Data download that includes a summary of the historic mining activities, mineralogy, references about these districts, and GIS files.
ON-007-08M Historic Metal Mining Districts of Colorado — GIS map of the historic mining districts with hyperlinks to text descriptions of these districts.
U.S. Geological Survey — For more on Climax-type porphyry molybdenum deposits see Open-File Report 2009-1215. Also, the USGS has more information on mineral deposit models. The USMIN project includes many publications with GIS downloads showing the locations and characteristics of select metal deposits in the U.S. including Colorado. The CGS reviews and comments on some of these publications prior to their release.
Russell L. and Lyn Wood Mining History Archive (at the Arthur Lakes Library, Colorado School of Mines) — established in 1995 through the generous donations of former Mines Board of Trustees member Russell L. Wood and his wife Lyn, the archive supports research on the history of mining, with emphasis on Colorado and the US West.
The Colorado School of Mines Museum of Earth Science in Golden and Denver Museum of Nature and Science both have numerous specimens collected from Colorado mines on display. The Friends of Mineralogy Colorado Chapter has several publications associated with their field trips and meetings that include metals and mining districts throughout Colorado. Also, the National Mining Hall of Fame and Museum in Leadville and the Western Museum of Mining and Industry in Colorado Springs have more on mining and minerals.