FLINT CREEK DISTRICT
Most of the mines of the Flint Creek (Philipsburg) district, which includes the Red Lion camp, are in a 3-square-mile area just east of Philipsburg. This district is the largest lode-gold producer in Granite County even though gold accounts for only 10 percent of the value of the ore. Silver forms the remaining 90 percent. Some lead, copper, and zinc have been produced but they are of no great economic importance. From 1950 through 1959 the Algonquin mine produced large tonnages of manganese ore, which yielded gold as a byproduct. The principal mines of the district are the Granite, Bimetallic, and Hope mines.
Ore was discovered at the Hope mine in December 1864, and lodes were soon located in many other places in the district and in the adjacent region (Emmons and Calkins, 1913, p. 191-193). The town of Philipsburg, just south of the Hope mine, was founded in 1867.
The Granite Mountain mine, the most productive in the Flint Creek district, was located in 1872. From 1875 to 1892 it yielded about $20 million in silver and gold and for a time was the most productive silver mine in the United States (Emmons and Calkins, 1913, p. 202-203). The Bimetallic mine, on the same ore shoot as the Granite Mountain, began operations in about 1882. Because of the fall in the price of silver, the mine was shut down in 1893 and was consolidated with the Granite mine in 1898 under the name of the Granite-Bimetallic Consolidated Mining Co. From 1898 to 1904 these mines produced silver ore valued at about $1 million a year, but in August 1905 they were again shut down because of the low price of silver and decreasing grade of the ore. In 1906 the mine was opened to leasers. With the exception of the depression years, 1930-32, the Flint Creek district maintained a substantial annual production through 1945, when activity slackened. From 1946 through 1956 only a small amount of gold was mined. No activity was reported from 1957 through 1959.
Early mining operations in the district were very expensive because of the remoteness of supply points. Milling costs were especially high; for example, salt, which was used in large quantities in silver mills, had to be transported from Utah and cost $120 a ton at Philipsburg in 1871. In 1883 the Northern Pacific Railway was completed through Drummond, only 30 miles from Philipsburg. A railroad from Drummond to Philipsburg was completed in 1887 (Emmons and Calkins, 1913, p. 192), and low-cost shipment of ore to smelters at Helena, Anaconda, and Great Falls was made possible. Some ore, however, was still treated in silver mills near the mines.
The gold production of the Flint Creek district before 1904 was estimated by Emmons and Calkins (1913, p. 201, 203) to be worth about $3,200,000, or about 155,000 ounces. Total production through 1959 was about 260,000 ounces.
The rocks exposed in the mineralized area east of Philipsburg comprise the upper part of the Spokane Formation of Precambrian (Algonkian) age and sedimentary rocks of Paleozoic age. These rocks are intruded by granite and granite porphyry of Cretaceous or Tertiary age and are folded and cut by numerous faults of small displacement (Emmons and Calkins, 1913, p. 28-126; 201).
The precious-metal deposits consist of silver-bearing veins in granite and in sedimentary rocks and silver-bearing replacement deposits in calcareous sedimentary rocks (Emmons and Calkins, 1913, p. 201-219). The Granite-Bimetallic lode, which produced the bulk of the ore in the district, is in the granite. This lode consists of pyrite, arsenopyrite, stibnite, tetrahedrite, tennantite, galena, sphalerite, and small amounts of pyrargyrite, proustite, realgar, and orpiment in a gangue of quartz, rhodochrosite, and calcite. This ore contained 20 to 30 ounces of silver per ton and from $1.50 to $3.00 worth of gold per ton. Much of the ore was enriched and secondary cracks are filled with pyrargyrite (ruby silver), argentite, and tetrahedrite (gray copper) and, locally, sphalerite and chalcopyrite. The secondary ore carried from 50 to 1,000 ounces of silver per ton and from $4.00 to $8.00 worth of gold per ton.
The replacement ore, which has been exploited chiefly in the Hope mine, consists of quartz, calcite, fluorite, barite, and rhodochrosite, and the ore minerals are argentite, chalcocite, and argentiferous tetrahedrite. Pyrite and galena are rare, because much of the ore was oxidized. There is almost no gold in this type of ore (Emmons and Calkins, 1913, p. 163).
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