By A. H. KOSCHMANN and M. H. BERGENDAHL - USGS 1968
Teller County is in the southern part of the Front Range, west of the city of Colorado Springs. The famous Cripple Creek district is the source of nearly all the mineral wealth of the county.
CRIPPLE CREEK DISTRICT
The Cripple Creek district is about 45 miles southwest of Colorado Springs, in the shadow of Pikes Peak. The leading gold producer of Colorado and the second most productive gold-mining district in the United States, Cripple Creek had a total gold output of 19,100,867 ounces through 1959.
Though prospectors were active in the Pikes Peak region as early as 1859, they overlooked the ores of Cripple Creek. In 1874, a few fragments of gold ore were found in the Mount Pisgah area, but they generated little sustained interest. Between 1880 and 1890, Robert Womack, an itinerant prospector and rancher, found gold ore in numerous shallow pits and diggings in the Cripple Creek area, which at that time was a cattle ranch.
Womack's persistence finally roused the curiosity of others, who bought his claims in 1891. At about this time W. S. Stratton became interested in the discoveries and noted that much of the ore which the prospectors considered to be galena was in reality a gold-bearing mineral that was later found to be the gold telluride, sylvanite. Stratton continued his investigations, and on July 4, 1891, he located the Washington and Independence claims on a barren, granitic-appearing outcrop that proved to be gold ore worth $380 per ton (Lindgren and Ransome, 1906, p. 130-132). Within a few months the hills swarmed with prospectors, and in February 1892 the town of Cripple Creek was founded.
By 1893 many of the major mines of the district, among them the Portland, Independence, Granite, and Strong, were in production. Labor strife in 1894 caused a temporary setback, but new mines, including the Vindicator, Golden Cycle, Victor, Isabella, and Cresson, were opened in the following few years. Peak production was in 1900, when 878,167 ounces of gold were mined (Henderson, 1926, p. 247). Activity slowly declined until 1934, when the-price of gold was raised.
The revived production in the late 1930's was further stimulated by construction of the Carlton drainage tunnel in 1941, which relieved many of the pumping difficulties found in the deeper mines. Output declined during World War II and increased thereafter, but it did not increase to the prewar level. Only a few mines were operating in the district in 1959.
The following brief description of the geology and ore deposits has been abstracted from reports by Lindgren and Ransome (1906), Loughlin and Koschmann (1935), and Koschmann (1949).
The ore deposits of the Cripple Creek district are within or at the margin of an irregular mass of Miocene fragmental rocks composed of stratified terrigenous sediments and volcanic breccia, collectively known as breccia according to local usage. These rocks occupy a steep-walled basin or caldera about 4 miles long and 2 miles wide, in granite, gneiss, and schist of Precambrian age. Locally the surrounding Precambrian rocks are capped by sandstone, grits, and volcanic rocks that are older than the fragmental rocks in the basin.
As the breccia accumulated in the basin, it subsided intermittently along steep faults. Subsidence also produced shear zones in the breccia and adjacent Precambrian rocks, and these were filled with dikes and irregular masses of latite-phonolite, syenite, phonolite, and alkaline basaltic rocks (lamprophyres). A small pipe of basaltic breccia, known as the Cresson blowout, cuts the fragmental rocks in the south-central part of the caldera.
The subsurface structure and configuration of the basin can be deciphered only in a general way. Available data show that the basin is composite in structure and comprises three minor basins or sub-basins separated by buried granite ridges and spurs. The basin walls, as determined from underground exposures, are irregular but in general steep. In most places their average slopes range from 46 to 80 degrees toward the center of the corresponding sub-basin.
In places, however, notably along the southwest wall, they overhang, and in places along the northeast wall they slope as little as 23 degrees; in still other places they consist of gently sloping benches with steep walls above and below.
Three stages of mineralization followed the recurrent fissure formation. The first stage is characterized by quartz-fluorspar veins and coarse pyrite. Gold tellurides, silver and copper tellurides, pyrite, sphalerite, galena, tetrahedrite, and the gangue minerals quartz, fluorspar, dolomite, ankerite, celestite, and roscoelite, mark the second stage. During the third stage, open fractures were filled with quartz, chalcedony, fine-grained pyrite, calcite, and local cinnabar.
The ore deposits in the Cripple Creek district occur in relatively short individual veins along narrow long vein zones. Many of these vein zones lie close to the margin of the breccia mass; others persist into the breccia; some cross the contact and extend into the adjacent Precambrian rocks for 2,000 feet or more. Most of the known vein zones are related in position and strike to the abrupt bends or recessions along the basin walls or to buried granite spurs or ridges within the basin.