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Exploring The Argo Mill and Tunnel: A Jewel in Colorado’s Mining Cities

Back in July 1859, the Colorado Gold Rush ultimately began, which marks this month as Colorado Mining Month. This month, we’re given an opportunity to look back on the state’s mining history and to explore the lasting impacts it had on Colorado’s mining cities, including the land, technology, and community as a whole. 

The Birth of Colorado’s Mining Cities

Gold was originally found in Colorado in 1858 in what is now downtown Denver. However, it wasn’t until 1859 that large deposits and veins of gold were discovered, creating the “Pikes Peak Gold Rush,” which we now know as the “Colorado Gold Rush.” Mining cities in Colorado first sprouted in Idaho Springs and Central City when the Gold Rush boomed, but through the years, other Colorado mining cities became recognized like Cripple Creek, Breckenridge, Telluride, Fairplay, and more.

Because of the Colorado Gold Rush, The Argo Mill and Tunnel was built in Idaho Springs to carry out the necessary milling process that follows mining. Swarms of prospectors flocked to Colorado during the years of the Gold Rush, and Colorado’s mining cities became home to countless miners, millers, and smelters—many of which were closely connected to the innerworkings of The Argo Mill and Tunnel.

The Argo Mill and Tunnel’s Role during the Colorado Gold Rush

When ore was mined from the natural Colorado rocks and land, it needed to be transported to a mill and processed into smaller chunks of pure gold to then be sent to smelters. The Argo Mill and Tunnel was the key site during the Colorado Gold Rush to do exactly that. The freshly mined ore was successfully transported through the tunnel from various mines to the mill in order to extract the gold from the valueless rock in which it was found. The extraction process used methods like amalgamation, cyanidation, flotation, and more. The Argo Mill and Tunnel significantly improved gold recovery rates making it the best milling site for Colorado mining cities. 

Technological Innovations

The Colorado Gold Mine and The Argo Mill and Tunnel specifically made significant technological leaps during the late 19th and early 20th centuries that set a precedent for future milling operations in other regions. 

The Argo Tunnel was one of the longest mining tunnels of its time and allowed for the most efficient ore transportation from Colorado mining cities directly to the mill, drastically reducing transportation costs. The tunnel was also used to drain water from the mines to prevent flooding and allow mining to go deeper than what was possible before.

The Argo Mill utilized innovative processing techniques like the stamp mill, which crushed ore into a fine powder to then extract the gold through amalgamation. Progressive milling technologies of cyanidation and floatation were crucial to The Argo Mill’s process. These technologies allowed gold to be extracted from low-grade ore that would otherwise be profitless.

Lasting Impact on the Colorado Mining Community

The astounding economic impact seen from the Colorado Gold Rush thanks to Colorado’s mining cities is already impressive and put Colorado on the map. The Argo Mill and Tunnel further impacted the state’s economy, not only by improving the profitability of mining operations but also by providing employment opportunities and helping develop communities surrounding the mill itself and near the many mining cities in Colorado that the mill worked alongside.

The Argo Mill and Tunnel is a testament to the miners of the Colorado Gold Rush. Its history remains well preserved today in Idaho Springs, celebrating its industrial heritage that has shaped Colorado.