The “Patch,” a deep crater-like hole on Quartz Hill, about one mile southwest of Central City, is an intriguing feature in this area. It was produced by glory-holing, a mining technique in which a deep tunnel is deliberately caved by blasting, so that ores above the tunnel can be removed. This glory hole was dynamited below an irregular mass of highly broken rock where many ore-rich [veins] converged. After the caving, ores were taken out through the remaining part of the tunnel.
The principal ore minerals of Central City and Idaho Springs are [native gold], [pyrite], [sphalerite], [galena], [chalcopyrite], and [tennantite]. Prospecting for uranium was carried out during the 1950s but no uranium was ever mined here.
The area has produced almost $200,000,000 worth of gold, silver, lead, zinc, and copper. A few mines still operate seasonally or on a small scale, but tourists, many of them riding Jeeps across the mountainous terrain to visit mines and ghost towns, are often more visibly active than the mines.
Georgetown, Empire, and Silver Plume
A few miles southwest of Idaho Springs, another mining area had a similar, though less productive, history. In 1859, [placer] and [lode] gold were discovered near what is now Georgetown. Placer mining dominated here between 1859 and 1863. Gravel and crushed rock from decomposed quartz and sulfide [veins] were washed through sluiceboxes in the same way as placer gravel, gold being caught in riffles or gunny sacking on the bottoms of the troughs. The veins were found to be decomposed to depths of about 40 feet; below this the gold occurred closely associated with sulfides such as [pyrite], [sphalerite], [galena], and [chalcopyrite], from which it could not easily be separated. However, smelters were developed in 1866 for treatment of these sulfides, and gold, silver, lead, and copper were recovered. Gradually, as the gold was worked out, silver and lead became the important products of the mines.
Sluicebox mining was a common sight near the early gold camps, where primary recovery was from [placer] deposits or decomposed quartz and sulfide [veins]. (State Historical Society of Colorado photo)
Leadville
[Placer] gold was discovered in 1859 in California Gulch, about seven miles north of the present town of Leadville. The rush that followed was short but sweet; the camp was called Oro—gold! About $5,000,000 was produced from the placer mines within two years, though by 1861 the area was all but deserted, for the easily won placer gold was gone.
