The Hidee mine is a tourist gold mine in Russel Gulch in the middle of the fabulously rich Central City gold mining district of the Colorado mineral belt. Like most mines in the district, the Hidee is located at an auriferous pyrite deposit which is characterized by oxidized ore near the surface and a pyritic sulfide composition at depth.
The Hidee adit was initially part of the adjacent Pittsburg mine, a mine that produced considerable gold. An adit and drift was dug to intercept the Pittsburg underground workings, but owing to labor problems was soon left abandoned for many decades. In the early 1980’s the claim was purchased and the mine converted to a tourist mine. A drift was cut to intercept the original shaft and in the course of digging, the Fay vein was discovered.
In the photo below, the Fay vein can be seen in the upper half of the image as a gold colored vertical band of pyrite which contains, according to the operators, 2 to 2.5 ounces of gold per ton. On either side of the vein copper mineral can be seen as the blue/green material.
Early mining characteristically removed the oxidized ore near the surface first which was more easily extracted by relatively simple means. That is, comminution by ball milling and isolation by shaker table or amalgamation. The deeper gold deposits, below the level of oxidized ore, were tied up in pyrite. This ore was much more complex to extract and required resources that many mine operators simply did not have. In the early days, the absence of rail or even passable roads impeded the sale of ore to mills and smelters.
Sulfide ores are commonly rid of the sulfur by roasting. This smelting process volatilizes the oxidized sulfur, replacing sulfide with oxide. Oxide ores may be pulverized and the gold separated by numerous methods. Common techniques applicable to oxide ores produced poor results with sulphuretted ores.
Today, the Hidee is operated as a tourist mine despite its relatively rich lode of gold. This is due to the cost of starting up a mine. Not only are there considerable costs associated with the mining process, the regulatory compliance costs are so substantial to a startup operation that very few people attempt to try it.
Even if one were able to navigate the regulatory compliance maze on a reasonable budget in a reasonable interval, the matter of smelting the ore to provide a crude bullion is a show stopper all by itself. For all intents and purposes, there is no gold smelting capacity in the US.
All in all, the Hidee Mine is well worth a visit. The guides were quite knowledgeable and very friendly. Many tourist mines dumb down the tour, but these fellows were on the level about technical details of the mine and geology. They especially like people who show an interest and some knowledge on the topic. They scheduled an extra tour for us at the end of the day and were cheerful about it.