Sahinen and Lyden identify this district by the name Mammoth. The South Boulder River drains to the north, flowing into the Jefferson River about two miles southeast of the village of Jefferson Island. The district was discovered in 1870 and has been an important producer of gold from lode mines. Sahinen states that Mammoth mine, with an estimated production of about $2,000,000 in gold-copper ore, is by far the most important mine. Other than the Mammoth, there is little information available about this district.
Due to the glaciation of the area, there have been many placer claims patented in this area, but only one, the Gold Bug, has been seriously worked (Sahinen 1935; Lyden 1948).
The area is occupied by rocks of the Archean Pony series which consist of gneisses and schists. Ore deposits occur in easterly striking fissure veins which roughly parallel the banding in the metamorphic rocks. The Mammoth quartz dike rose 100 feet above the face of the mountain near the summit. The dike was believed to be an extension of the Mineral Hill zone on the other side of the mountain (Sahinen 1935; Wolle 1963).
The ore from the district was first worked in a 10-stamp mill erected on the Grand Central claim. Other important early lode claims include the Leviathon, Buckeye, Sultan and Bullion (Leeson 1885).
When the town of Mammoth was visited by Wolle (1963), it had recently been sold and was slated for destruction the following year. However, at the time, the remains of homes, the old mill and several broken tram towers were observed.
BOUNDARIES OF THE DISTRICT
Sahinen (1935) places the district on South Boulder Creek, about 12 miles southwest of Jefferson Island. Figure 1 shows the district as defined by the AMRB (1994) and a smaller area delineated as the location of the district defined by Sahinen (1935). It includes the Mammoth and most of the other lode claims.
HISTORIES OF SELECTED MINES
The Bismark mine is located about three miles south of the Mammoth near the forks of South Boulder Creek. It is discussed in a separate district report (See Bismark - 114).
The Gold Bug mine is the only patented placer mine in the district that has been worked profitably (Lyden 1948).
Highland Mary Lode
The Highland Mary Lode is located in NW section 13 T2S, R4W on McGovern Creek about 1.25 miles west of the Mammoth mine. The claim was located by B. W. Wilson around 1900. The claim was surveyed in 1906 (MS# 7952) and sold to John N. Kirk in 1906. A patent was issued to Kirk in 1907. Later the ownership was acquired by Basil "Babe" Nicholson.
The mine survey of 1906 listed a log blacksmith shop and equipment such as rock drills, shovel, picks, hammers, an ore car and blacksmith tools. These items were valued at the time at $200. Sometime after the survey, a second cabin was built for occupation. Other mining related improvements were also added. These included: a log-crib dam, a water wheel and an arrastra. There is no production recorded for the mining claim (Beck 1987).
The Mammoth mine is located on the east slope of the South Boulder Creek Valley. The mine is developed by five adits with a combined distance of 3,000 feet and a vertical range of 1,000 feet. The mine was discovered by John Hughes and James Howe and was the first lode discovery in the South Boulder district. Initially, near-surface ores were worked at a good profit. The mineralization of the mine appears to be a westward extension of the Mineral Hill zone of the Pony district. The mine produced iron oxide ore with values of gold, silver, and copper (Tansley, Schafer and Hart 1933).
Ultimately, the mine was to become the largest producer of the district. In 1905 the mine was operated by the Mammoth Mining & Power Company. Thirty men were employed in a series of tunnels ranging from 300 to 700 feet. An aerial tram carried the ore from the mine to the newly completed mill. This 100-ton concentrator was equipped with crushers, rolls, and nine Wifley tables. The mine reported two fatalities in 1906. One worker was killed by a premature blast and another by picking into an unexploded round (Walsh and Orem 1906; Sahinen 1935).
The mine operated intermittently from 1907 to 1914. After 1924 the mine was worked by the Liberty Montana Mining Co. and produced copper concentrates with gold and silver values. In 1926 the company spent over $50,000 for equipment and developmental work. Thereafter the mine shipped 1,000 to 3,000 tons of ore per month until 1940. Thirty men were employed in nine stoper machine shifts and two drifter machine drifts each 24 hours. (Sahinen 1935; Lorain 1937; WPA 1940).
The mine initially produced its own power from a storage dam. However, the dam was partly destroyed in the early 1930's and the company was forced to buy part of its power from Montana Power. Two pelton wheels were operated under a 285-foot head; they were directly linked to two Sullivan compressors that were capable of supplying 2,150 cubic feet per minute (Lorain 1937).
The ore from the mine was trammed 4,000 feet from the working face to the mill. There it was dumped into a 150 ton coarse-ore bin that fed to a 12 x 18 inch jaw crusher. A 18-inch belt conveyor carried the rubble to the fine ore bin which fed to another conveyor that carried the ore to a 4.5 x 6 foot Marcy-type ball mill that turned at 28 rpm's. This ball mill worked in closed circuit with a Dorr duplex classifier. Between the mill and the classifier a Denver Sub-A unit flotation cell was placed which recovered about 60% of the ore values. Overflow from the Dorr classifier passed to a K & K flotation machine; the froth of which passed to a K & K cleaner. Tails from the cleaner cell returned to the ball-mill feed. Tails from the rougher machines went to two Wilfley tables which made the final tail, a finished concentrate and a middling that was returned to the ball-mill circuit. Concentrates went to a Dorr thickener and then to a 4 foot Oliver filter. Concentrates were then shipped in 4 or 4.5 ton truck loads to the railroad at Jefferson Island and from there transported to the Anaconda Smelter. Total recovery was estimated to be 92% of the ore values (Lorain 1937).
From 1905 to 1935 the mine was credited with 53,377 ounces of gold, 113,938 ounces of silver, and 1,088,111 pounds of copper from 214,149 tons of ore. Most of the production occurred after the Liberty Montana Mining Co. took over the operation in 1924 (Lorain 1937).
The Surprise mine is located in the Tobacco Root foothills at an elevation of 4,700 ft about 1.5 miles southeast of the head of Jefferson Island. The mine worked a strong fissure zone in feldspathic sandstone or Upper Beltian arkosic sandstone. The oxidized ore contains free gold in hematite or limonite mixed with quartz (Tansley et al. 1933).
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