Leadville mining district
On April 26, 1860, Abe Lee made a rich discovery of placer gold in California Gulch, about a mile east of Leadville, and Oro City was founded at the new diggings.
Prospectors traced the cerussite to its source, and by 1876 had discovered several lode silver-lead deposits, setting off the Colorado Silver Boom.
Unlike the gold which was in placer deposits, the silver was in veins in bedrock and hard rock mining was needed for recovery of the ore.
Leadville is a high mountain town and the winters are long and bitterly cold; many miners died of exposure and starvation.
Many small shanty towns grew up around Leadville, including Poverty Flats, Slabtown, Finntown, and Boughtown.
The primary ores of the CMB were generally deposited as mixed metal sulfide mineral veins containing pyrite, galena, sphalerite, chalcopyrite, and gold, silver, and copper.
[12] The district is a highly faulted area, intruded with Tertiary quartz monzonite porphyries, on the east side of the Arkansas River graben, part of the Rio Grande Rift system.
Paleokarst features include isolated eaves and sinkholes as well as integrated cavern systems that are mineralized and can be traced from insurgence to outlet.
[14]Mining, mineral processing and smelting activities in the area have produced gold, silver, lead and zinc for more than 130 years.
Wastes generated during the mining and ore processing activities contained metals such as arsenic and lead at levels posing a threat to human health and the environment.
Since 1995, EPA and the potentially responsible parties have conducted removal and remedial activities to consolidate, contain and control more than 9,400,000 cubic feet (350,000 cu yd) of contaminated soils, sediments and mine-processing wastes.
As of September 2011, most of the cleanup had been completed so current risk of exposure is low, although pregnant women, nursing mothers and young children are still encouraged to have their blood-lead levels checked.
The Yak tunnel, 3.5 miles (5.6 km) long and built between 1895 and 1923 to drain the southern part of the district, has its outlet in California Gulch east of the town of Leadville.
"[18] On 27 February 2008, the US EPA began pumping 150 US gallons (570 L; 120 imp gal) per minute from the tunnel system, to relieve water pressure upstream from the blockage.
The "Route of the Silver Kings" is a driving tour of the 20-square-mile (52 km2) historic mining district surrounding Leadville.
The Matchless mine and cabin, former home of Baby Doe Tabor, is open as a tourist attraction during the summer.
