DON AND SARA PARSONS

Minerals - Fossils - Carvings

2808 Eden Lane
Rapid City, SD 57703
605 348 0937 FAX 605 341 2568

Bald Mountain Mining Company Crucibles

   The company owned or controlled about 2000 acres in Lawrence county, SD. They mined over 3 million tons of ore from a large number of mines. They were the second largest Gold mining company in North America at that time, only Homestake was bigger. The mines were all near surface and each offered various problems in getting the Gold and Silver out of the rock. It's been estimated that they lost half of the Gold and all of the Silver in processing the more refractory ores.

   Some ores were crushed to sand size and mixed with Mercury or roasted in ovens and submitted to chlorination. Others were sent to smelters as far away as Denver, Chicago and Omaha. The easy ore [ Gold in quartz ] was crushed by their stamp mills, gravity separated and refined in these crucibles. An interesting aside is that the stamp mills added iron by adhering to the Gold flakes as the stamps wore. This was removed in the oven by adding pure fine silica which bonded with the iron in the melt, carrying it off as overflow and coating the outside of the crucibles with the green slag.

   There is a "History of the Bald Mtn. Mining Co. and it's Predecessors". This is a 1991 historical study commissioned by Wharf Resources. I hope to buy a copy or at least look it over when I find one.
 

B6-18 Crucible
17" tall, 12" diameter
Weight 40 lbs.

   Oh yes, the crucibles were also called "cupels", the process was known as cupellation. Though this word was mainly used with Silver processing, the word came over into Gold processing. Today a cone is used to melt the Gold, flux is added and it's allowed to cool. The cone is upended, slips off and the slag is tapped with a hammer. The Gold breaks free and a thin slice is cut from the Gold to remove the slag/gold interface. This is then re-melted with the next batch.

   The cellar storage room had been accessible only through a trap door in the center of the mill. When a new plank floor was installed they blocked this access. The crucibles found there had to have been used prior to this time. The mines and mill were shut down during WW 2, after the war they were allowed to re-open. I'm not certain but I believe the new plank mill floor was added at that time.

   The company assayer stated that a crucible was used until a hole was burned through the side or it was broken by mishandling. When this occurred they were crushed and the Gold was recovered, each crucible contained 3 to 4 ounces of Gold depending on how long it had been in use.

We offer this piece of gold mining history for $1800.00. We have three of these available for sale to museums or private collectors

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