In 1859 prospectors from Georgia found gold in gravel deposits in Cherry Creek just south of Denver. Later prospectors discovered gold in vein deposits around present-day Blackhawk and Central City. The rush to Colorado was on. Gold production from the central Front Range through 1990 was 7.3 million ounces. Since 1859 Colorado’s mines have produced about 45 million ounces of gold.
Colorado’s largest gold discovery was the Cripple Creek district in 1893. This one district alone produced over 22 million ounces of gold. The Cripple Creek district contains the largest remaining gold mine in Colorado with an estimated annual production of 224,000 ounces in 2008.
Gold prospectors in the Leadville area kept finding an unknown dark mineral in their gold pans. This was later recognized as silver ore and lead to the development of the Leadville, Gilman, and Kokomo districts, which produced about 1.9 million tons of zinc, 1.3 million tons of lead, 333 million ounces of silver, and 3.6 million ounces of gold through 1998. The Black Cloud Mine was the last working mine in the district and it closed in 1999.
Molybdenum was discovered in the Climax area around Fremont Pass north of Leadville in 1879. The strange greasy metal had no known uses at the time of its discovery; however, by World War I, it had come to be used as an alloy for hardening steel for armaments. The Climax Mine continued to increase production through World War II and into the 1970s. The state of the art Henderson Mine in Clear Creek County opened in 1976. Both mines produced until a price crash occurred in the mid-1980s. The Climax Mine was placed in suspension in 1986, and only the Henderson Mine continues to produce molybdenum in Colorado. Climax bagan the prcess of re-opening in 2008, but the re-opening was suspended because the spot price of molybdenum fell from over $30 per pound to under $10 per pound in a matter of weeks.
Many uranium deposits were discovered in the southwestern portion of Colorado and in the Front Range during the 1950s. The most significant uranium mine was the Schwartzwalder Mine between Golden and Boulder. As recently as 1997 the mine produced about 500,000 pounds of uranium oxide. The mine was closed in 2000.
Colorado is famous for its aquamarine, rhodochrosite, beryl, and diamond gemstones. Diamonds were discovered in 1975. The Kelsey Lake Mine in Larimer County began commercial production in 1996 and quickly produced some outstanding gem quality diamonds-as large as 14 and 26 carats.
Sand and gravel, crushed stone, gypsum, limestone, clay, and other rock materials are important commodities that provide the basic infrastructure materials for Colorado’s booming economy of the late 1990s and 2000s. Production of these commodities has increased steadily over the past decade. The Yule Marble quarry in central Colorado produces some of the finest white marble in the world. Marble from the Yule quarry was used for the Tomb of the Unknown Soldier and part of the Lincoln Memorial in Washington, D.C.
Companies are using a solution-mining process to produce sodium bicarbonate (baking soda) from bedded nahcolite deposits in the Piceance Basin of northwest Colorado. The newest operator, American Soda LLC, plans to use an additional process to convert the sodium bicarbonate to sodium carbonate (more commonly known as soda ash—used primarily in the glass industry). American Soda plans to produce a million tons of soda ash in 2001, its first full year of operation.
Coal mining in Colorado began soon after the first settlers and miners arrived in the Front Range. The area around Boulder and Weld counties once had over 100 producing coal mines. Coal is still produced, primarily from open cut and underground mines in the northwest part of the state. Production in 2004 was over 40 million tons making Colorado number 6 out of 30 coal-producing states. However, in 2010 Colorado dropped to 11th in the nation.