Lode mining in the Dunkleberg mining district, located on the northwest corner of the Flint Creek Range and southeast of Drummond, has been conducted intermittently since the 1880s. The Forest Rose and several other claims were staked in 1884. Other early claims include the Mountain Chief, Pearl (or Happy New Year), Kirkendal, and Monarch (or Old Tanglefoot). In the early years of the Twentieth century a small, undocumented lead smelting operation was tried on the Pearl claim, with apparently little success. Most of the district's production has come from the Forest Rose, Wasa and the Jackson mines. Up to 1916, about $200,000 in silver and lead had been produced in the district, about half of which was produced by the Forest Rose (Pardee 1917; Sahinen 1935; Popoff 1953).
World War I brought renewed activity to the district. The Forest Rose and a new claim, the Wasa, dominated the production with around 2,000 tons shipped. However, during the Depression, activity again ceased in the district. During World War II the mines revived and 113,000 tons of ore were produced by the combined Forest Rose and the Wasa operation. The Forest Rose Syndicate built a 100-ton flotation mill near the Forest Rose mine and controlled all the claims between the Forest Rose and the Wasa. From 1941 to 1947 this electrically powered mill treated 113,000 tons of lead-zinc ore worth $875,000 (Popoff 1953).
The Dunkleberg district is underlain by sandstones and shales of Cretaceous age. Exposed successively to the south are rocks from the Kootenai, Ellis, Phosphoria and Quadrant formations. The district's sandstone and shale is intruded by sills of diorite and gabbro up to 1,000 feet in thickness. Near the contact with the intrusives, the native rock has been metamorphosed, metamorphism does not extend far from the contact. Along Dunkleberg Ridge, most of the lodes containing lead, zinc, silver and other metals are simple quartz veins in fissures that follow bedding planes or cut across the sediments and diorite sills. The veins are usually narrow, but in places widen to flat lenses three or four feet thick. The Wasa Lode, the exception, worked a contact metamorphic deposit. The most important ore in the district was argentiferous galena and cerussite. Sphalerite was common in some of the mines (Sahinen 1935).
BOUNDARIES OF THE DISTRICT
From Hall, a small community in the Flint Creek valley south of Drummond, the mines can be reached by a road up a low spur known as Limestone Ridge. A former ore-hauling road goes up Dunkleberg Creek from Jens, a station on the Northern Pacific Railroad along the Clarks Fork River. Sahinen (1935) placed the Dunkleberg district to the south of Jens.
The mines and prospects of the district were confined to an area two miles wide and five miles long in the foothills of the Flint Creek Range (Sahinen 1935).
Popoff (1953) places the district in the Flint Creek Range, west of the Continental Divide and south of the Clark's Fork River.
Figure 1 shows the district essentially as described by Sahinen (1935).
HISTORIES OF SELECTED MINES
The Forest Rose Mine is located a mile north of the Wasa on a steep slope west of Dunkleberg Creek at an elevation of 5,500 feet. The mine was first located and claimed by Frank Carnes in 1884 and is on the patented Forest Rose and Acrobat claims. Other claims in the area include the Trapeze, Monitor, Bellaire and Little Mack. The upper levels of the mine were extended in the first years of the century, resulting in the production of oxidized ore. The mine was said to have produced $100,000 in silver-lead ore by 1916. When visited in 1916, the size of the dumps indicated extensive underground development through several collapsed workings. The ore consists of quartz, limonite, and a little galena and pyrite. These occur in replacement deposits in limestone on or near the axis of the Dunkleberg anticline (Pardee 1917; Popoff 1953).
When visited in 1917, the mine was being prepared for reopening. The mine recorded production almost continuously from 1918 to 1927. During World War II the Forest Rose and the Wasa mines were once again reopened. Together they produced 113,000 tons of ore, nearly the entire district production. The main adit is at an altitude of 5,150 feet and from its portal on the West Fork of Dunkleberg Creek is driven 480 feet west into the hill. From this adit are 3,000 feet of underground workings. The most important is the south or Monarch drift which is 1,800 feet long and is about 200 feet below the adit portal of the Monarch. Extensive mining was also done from a 400 feet winze. The preferred mining method employed was shrink stoping (Pardee 1917; WPA 1941; Popoff 1953).
Around 1941 the Forest Rose Syndicate built a 100-ton (rated) concentrator to work the mine's ore. At the mill the ore was crushed to less than two inches by a 10 x 20 jaw crusher, and then ground to less than 65 mesh in a ball mill in a closed circuit with a rake classifier. The product was conditioned for lead flotation and taken to a bank of eight cells for lead concentration. The ore was then re-conditioned for the zinc circuit. Zinc concentrates were sent to the Anaconda zinc plant and lead concentrates were sent to East Helena. The mill could run 90 tons of Forest Rose ore or 65 tons of the Wasa or Monarch ore in a day (Popoff 1953).
The Hatta mine is near the top of the slope east of Dunkleberg Creek, about two miles northeast of the Forest Rose. A large production of silver - lead was reported several years prior to 1916, but production was discontinued when zinc blende became too abundant in the ore. The mine is in an area occupied by diorite or gabbro (Pardee 1917).
The Jackson mine is located half a mile south of the Hatta and was reported in 1916 to have had $25,000 worth of production in prior years. When visited, the workings were inaccessible but the dumps indicated extensive underground development. Ore was composed of lead carbonate and limonite in a honeycomb of quartz (Pardee 1917).
Monarch or Old Tanglefoot
The Monarch mine was apparently claimed in the late 1880s. However, it did not achieve significant production until it was worked in conjunction with the Forest Rose Syndicate operations from 1941 to 1947. One of the most important drifts in the Forest Rose is on the Monarch Claim; the Monarch drift is 1,800 feet long and is 200 feet below the Monarch adit level (Popoff 1953).
Pearl or Happy New Year
The Pearl claim is located half a mile north of the Wasa mine. A small blast furnace was erected on the claim to smelt the lead ore. In 1916 the adit had collapsed, but the dump showed quartz and limonite ore with some galena and copper stain (Pardee 1917; 1918 ; Emmons 1913).
The Summit claim is half a mile north of the Pearl. Two short adits expose a vein on a bedding plane in sandstone of the Colorado formation. Five carloads of ore were reported to have reduced to 60 ounces of silver per ton and 40 percent lead (Pardee 1917).
The Sunset claim is on the creek east of Dunkleberg Creek near stream level and about 2.5 miles north of the Wasa mine. A 100 foot long adit into a diorite and gabbro sill follows a narrow vein. Ore from the vein is quartz and partially unoxidized galena. When the mine was visited in 1916 a load of this ore was being prepared to ship. The ore was reported to carry 30 or 40 ounces of silver per ton (Pardee 1917).
The Wasa mine is on Dunkleberg Ridge near the head of Douglas Creek at an elevation of about 6,700 feet. The mine is situated about a mile south of the Forest Rose on the Jackpine claim. The claim, discovered in 1910, has been developed through four adit levels driven eastward with a total length of 1,500 feet. Three of the adits, the No. 1, No. 2 and No. 3 or Zimmer Jack were located together while the No. 4 adit, the Kirkendall tunnels are 1,000 feet to the southeast and higher. The main Kirkendall adit is 740 feet long; the lower Kirdendall adit is 400 feet long. The first three tunnels were cut off by a fault. Exploration was also conducted by the Makeever Brothers of New York City who drilled 3,700 feet of diamond-drill holes. Ore extends from the surface 180 feet down to the lower adit. The ore in the lower tunnels is a hard, flinty rock derived from shaly limestone by replacement with silica. Pyrrhotite, pyrite and chalcopyrite accompanied the silica. The upper tunnel ores show abundant pyrite and tetrahedrite cut by zinc blende. While the mine produced 2,000 tons of ore during World War I, the mine's greatest production was during World War II when it was operated in conjunction with the Forest Rose. During the war the Forest Rose Syndicate produced 98.2 percent of the district's ore production (Pardee 1917; Popoff 1953).
Emmons, William Harvey and Frank C. Calkins
1913 Geology and Ore Deposits of the Philipsburg Quadrangle, Montana.
U. S. Geological Survey, Professional Paper 78.
Pardee, Joseph Thomas
1917 The Dunkleberg Mining District, Granite County, Montana.
U. S. Geological Survey
, Bull. 660, pp. 241-247;
(abst.) Washington Acad. Sci. Journal
, Vol. 8, p. 249.
1918 Ore Deposits of the Northwestern Part of the Garnet Range, Montana. U. S. Geological Survey, Bulletin 660-F pp. 159-239; (abst.) Washington Academy of Science Journal, Vol. 8, p. 290.
1921 Phosphate Rock Near Maxville, Granite County, Montana. U. S. Geological Survey, Bull. 715-J, pp. 141-145; (abst.) Washington Acad. Sci. Journal, Vol. 11, No. 16, pp. 393-394.
Popoff, C. C.
1953 Lead-Zinc Deposits of the Dunkleberg District, Granite County, Montana. U.S. Bureau of Mines, Reports of Investigations 5014.
Sahinen, Uuno M.
1935 "Mining Districts of Montana", Thesis, Montana School of Mines, Butte.
Work Projects Administration (WPA) Mineral Resources Survey
Montana Mine Index, An Alphabetical Index Arranged by Counties, Districts and Mines of Information on Montana Mines from 1867-1940
. Montana School of Mines, Butte.