The history of the Territory and State of Colorado is inextricably tied to base metals and precious metals. Gold and silver strikes were a big draw for the migration of population to Colorado from the 1859 Pikes Peak Gold Rush onward.  A map of the ore geology of Colorado reveals a few key districts or zones of enhanced mineral abundance. The Colorado Mineral Belt (CMB) is a band of ore deposits that is positioned diagonally across the middle of the mountainous part of the state, SW to NE, roughly from Durango to Boulder.

Other districts containing economically viable ore bodies exist outside of the CMB, notably the Thirtynine Mile Volcanic Field west of Colorado Springs. While rich deposits of gold were found near Central City and many other locations in the CMB, the relatively rare  gold/tellurium ore found near Cripple Creek and Victor on the periphery of the Thirtynine Mile Volcanic Field have provided approximately half of all the gold mined in Colorado. Gold has an affinity for tellurium and may be found combined with it in the form of the mineral calaverite.

In particular, the Cresson mine near Cripple Creek has been an especially rich producer of gold. In November of 1914, a 4 m x 8 m x 13 m cavity or “vug” at the 1200 ‘ level was found to be lined with gold telluride and other minerals.  Depending on which source you believe, it is reported that from 20,000 to 60,000 ounces of gold were removed from this small space.

The Cripple Creek volcanic complex is a highly altered, highly brecciated formation that has been described in detail elsewhere. The link provides a more detailed description and a bibliography.