The Elkhorn district was prospected early in the history of the State and numerous quartz locations were made in the years preceding 1870, but the district did not attract attention until the A. M. Holter lode became a producing mine.
This property, later known as the Elkhorn mine, has been the principal and, in fact, almost the only producer of the district, and was for many years one of the prominent silver mines of the country. The history of the mining industry of this district is therefore the history of this mine.
The Elkhorn property was sold by its original locators to A. M. Holter, after whom the claim has been named. Mr. Holter organized the Elkhorn Mining Company, and the mine has since been known as the Elkhorn mine.
A 5-stamp wet crushing free-milling plant was erected by the first owners, and as the surface ores were free milling and yielded readily to simple amalgamation, satisfactory results were realized in the early history of the property. With increased depth, however, the oxidized ores became refractory and the loss in treatment became as high as 50 percent of the silver values.
In 1881 the mine was developed to a depth of 300 feet, and the nature of the ore made it evident that a new mill would have to be erected and chloridization adopted. Owing to a disagreement among the owners and the necessity of enlisting new capital, the property was idle for the greater part of the year 1882, though it yielded 4,285 ounces of fine silver during that year.
In 1883 the property passed into the possession of the Elkhorn Mining Company, a new hoist was erected, and a 10-stamp chloridizing mill was put up, with a capacity of about 11 tons a day. The ore was stamped fine, roasted, and amalgamated in combination pans without grinding. The result was a saving of 90 per cent of the values and a bullion product aggregating $188,375 in silver and $2,320 in gold for the first ten months after installment. The bullion product was fine in silver, with a little gold, the principal impurity being copper.
The old Elkhorn Company subsequently increased its battery to and then to 25 stamps and worked the mine down to the 800-foot level, where lean ore was encountered, and some doubt was expressed as to whether the property was not worked out.
In 1888 the Montana corporation sold out to a new company organized in London, which took the name and property of the old corporation, remodeled the mill, and instituted a policy of vigorous development, under which the mine has yielded 6,500,000 ounces of silver and 5,000 ounces of gold since 1888. The total production of the mine has been computed by Mr. Walter S. Kelley, the manager of the property, from the company's books. The figures are given in round numbers only, and those for the earlier period are only approximate.
From 1884 to January, 1900, the mine was in continuous operation, save for a short time in 1886, when an accident to the pumps resulted in the flooding of the mine up to the 500-foot level for several months.
In 1896 the ore in sight was nearly exhausted, and preparations were made to abandon the mine, but Mr. Walter S. Kelley, who at that time became general manager of the property, by careful exploration work disclosed new ore bodies, and continued to work the property until December, 1899.
In the autumn of 1899 it became apparent that the expense of pumping, which necessitated heavy fuel bills, combined with the small extent and low grade of the ore in sight, would not warrant the further operation of the mine. The cost of the ore extracted had steadily risen during the last few years until in 1898 it reached a total of $15.60 per ton, while the expense of milling increased to $9.50 per ton. It was therefore decided to close down and abandon the property.
The development of the Elkhorn has played an important part in the settlement and betterment of the State. The monthly pay roll aggregated over $15,000, as besides the men employed at the mine and mill a large number of wood choppers were regularly at work.
The town of Elkhorn, a settlement with a population of about 600, was built and maintained practically by this one mine, and the supplies shipped to the district for mine and town kept the railroad line busy for many years. The passing into history of this great property is felt not only at the town of Elkhorn, but in the ranches, for whose produce it furnished a market, and in the parts of the State from which it drew supplies.
The former inaccessibility of the district, situated as it was in the heart of the mountains and until recent years remote from railroad communication, deterred active prospecting for a long time; moreover, in the early years of the Elkhorn mine, supplies, particularly salt, were very expensive, so that the cost of treatment was heavy.
In 1886, the Northern Pacific Railway built a branch line to Wickes to get the ore-carrying business of the Alta and Comet mines. About two years later the marvelous development of the Butte cooper deposits induced this company to begin an extension of this branch southward to that city.
At the same time the Montana Central, now a part of the Great Northern system, was under construction, and a railway-building contest began, with Butte as the objective point. The Montana Central secured the more favorable right of way, and the Northern Pacific line, after being built to Bernice, was not completed. Both roads pass through Boulder, the county seat, 12 miles west of Elkhorn, so that a year later the Northern Pacific Company was induced to build a branch line through the Boulder Valley and up the gorge of Elkhorn Creek.
The building of this road was a difficult piece of engineering, as the grade to be overcome was excessive, but by the use of short loops a road was constructed on which short trains could be hauled. A triweekly train service was established, making it possible to ship the silver-lead ores which were discovered in great abundance in the deep workings of the Elkhorn mine, and which were also found to a limited extent in other properties in the district.
Source: United States Geological Survey Twenty Second Annual Report 1900-1901 Part 2 Ore Deposits.