The ghost town of Caribou, Colorado, sits a few miles west of Nederland. As a group the mining towns of Caribou, Nederland, and Ward reside at the northeastern extreme of the Colorado Mineral Belt. This mineral rich formation cuts diagonally across the state, terminating near Durango in the southwest part of Colorado.

Every western state  has its mining districts.  The eastern reaches of the USA have hard rock mining districts as well. The Appalachians have a long history of hard rock mining. An example of eastern hard rock mining activity is the Foote spodumene mine in the Kings Mountain district in North Carolina.

The Ghost Town of Caribou, Colorado (Copyright 2009 all rights reserved)

The Ghost Town of Caribou, Colorado (Copyright 2009 all rights reserved)

While the Caribou district was previously known primarily for silver and tungsten, current hard rock mining operations by Calais Resources is targeting silver and gold. A blurb on the Calais website says that they do not use cyanide extraction in Colorado.

Calais Resources Comstock Shaft (Copyright 2009 all rights reserved)

Calais Resources Comstock Shaft (Copyright 2009 all rights reserved)

 This weekend the town of Nederland is celebrating its mining history with a miners festival. There were feats of strength and skill on display.

Hand drilling competition in Nederland July 2009

Hand drilling competition in Nederland July 2009

 Across town at the Mining Museum, a 1923 Bucyrus 50-B steam shovel was in operation. This 130,000 lb beast was powered by an antique air compressor this afternoon because the boiler is not servicable. It turns out that this very machine was one of 25 taken to the Panama Canal to move dirt and rock. All were scrapped at the canal but this one. The canal was finished in 1914, so it must have been used for modification of the canal workings.

This machine was in service at the Lump Gulch Placer a few miles south of its present location until 1978.  Bucyrus is still an ongoing concern in the mining equipment business.

Bucyrus 50-B Steam Shovel (Copyright 2009 all rights reserved)

Bucyrus 50-B Steam Shovel (Copyright 2009 all rights reserved)

As one drives into the Ward area from the north, the rock type evident in the road cuts changes. South St. Vrain canyon is largely granitic in nature. As one moves south into the Mineral Belt, the road cuts plainly reveal that a new dominant mineral type is present. Hematite or other iron oxide species are extensively represented in the rock.

My reading indicates that many metal ore bodies are the result of extensive hydrothermal modification of fractured or disturbed formations. Metal sulfide saturated, superheated water penetrates a disturbed formation leaving precipitates forming vein structures. In this way, many metal species are mobilized on the basis of solubility properties and are transported and concentrated leaving deposits enriched in a variety of useful metals.

The superheating of deep ground water and the subsequent partitioning and concentration on the basis of physical properties like solubility and volatility are what make the recovery of many elements possible. Without these concentration mechanisms many scarce elements would be too diluted in the parent formation to be feasibly isolated commercially.

Pyrite vug from a tailings pile (Copyright 2009 all rights reserved)

Pyrite vug from a tailings pile (Copyright 2009 all rights reserved)

What Th’ Gaussling has found is that, while a PhD in Organic Chemistry isn’t entirely useless as a background for understanding rocks, it is closer to useless than I’d like. Edgemicated as I may be in a skinny band of chemistry, I have a lot yet to learn about minerals and petrology.

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