Mining began at Aspen in 1880. Here, as at Leadville, intrusion of [granite] [porphyry] into or near the Leadville Limestone had broken and deformed the layers, and ores were deposited in fissures and as replacements during cooling of the intrusions. The intricacy of faulting which controls the ore pockets in the limestone is well shown on the map of [Aspen Mountain] in Chapter II.
[Glaciation] occurred in this area, and glacial deposits cover most of the ore bodies and outcrops so that little [bedrock] is exposed. Mapping was accomplished by extrapolating to the surface the bedrock patterns shown in mine pits, shafts, and tunnels.
Aspen produced some of the richest silver ores in the world, and thrived as a boom town for most of two decades. In 1888 the value of ores produced reached over $7,000,000; the next year it topped $10,000,000. After the silver crash of 1893 production declined rapidly; the last mines were closed in the 1920s. Total production of silver, lead, zinc, and copper reached about $100,000,000. There was virtually no gold in the ores at Aspen.
Creede
Creede and its mines are located in an area of Tertiary [rhyolite] and dacite, light-colored volcanic rocks.
Happy Thought Mine Amethyst Mine West Willow Creek AMETHYST [FAULT] Last Chance Mine Del Monte Mine Commodore Mine Jackpot Mine Coppervein Mine Bachelor Mine BULLDOG MOUNTAIN FAULT Kansas City Star Mine Commodore Tunnel Mustang Tunnel Nelson Tunnel Exchequer Mine SOLOMON FAULT CAMPBELL MOUNTAIN Holy Moses #2 Holy Moses Mine Ridge Mine Solomon Mine Monte Carlo Mine Mollie S. Mine East Willow Creek Ramey Tunnel Dora Belle Mine Mammoth Tunnel Homestake Mine Mammoth Mine MAMMOTH MOUNTAIN Nancy Hanks Mine Pipe Dream Mine THE NARROWS Windy Gulch CREEDE Willow Creek
The Creede district ranks as one of the most productive silver areas in the United States. It came into being largely as a result of a discovery by N.H. Creede in 1889. When exploring in this area, he was reported to have exclaimed “Holy Moses!” on examining a rich piece of ore, thus giving the name to the mine which initiated the rapid development of the district. By the end of 1892 the Holy Moses and nearby mines had produced ore valued at more than $4,000,000. The area was so rich that it managed to survive 1893’s great decline in the price of silver; by 1920 almost $42,000,000 in gold, silver, lead, and zinc had been mined there.
The ores, silver-bearing [galena], [sphalerite], [native gold], [pyrite], and [chalcopyrite], are in quartz or amethyst [veins] in faulted and shattered Tertiary volcanic rocks. Nearly all the ore deposits lie along a complex system of vertical [faults], the Amethyst fault zone, which runs more or less northwest-southeast through this region. Both the faulting and the enrichment of the fault fissures are believed to have taken place in mid-Tertiary time, shortly after deposition of the volcanic host rocks.