Known for its chromite deposits, the Silver Run district is located southwest of Red Lodge on the Silver Run Plateau in the Beartooth Mountain range. Two prospectors, working for J. F. Brophy of Red Lodge, located the first chromite on the Four Chromes claim in 1916. M. E. Martin, another local prospector, became interested in the mineral and took up the search, locating all the other known chromite deposits in the area before he died in 1937 (James 1944).
The rugged region consists of high plateaus, ranging from 10,000 to 11,000 feet in elevation. Rock Creek, Lake Fork of Rock Creek, and their tributaries flow through deeply incised glaciated valleys characterized by steep walls and rounded bottoms. The underlying rock is primarily granite and gneiss, while the sequence of metamorphic rocks includes hornblendite, hornblende schist, quartzite, and serpentine, the host rock for chromite. Younger rocks, represented by diorite, granodiorite porphyry, syenite porphyry, and pegmatite dikes, cut through the underlying rocks, and the entire region is crossed by numerous faults. The chromite deposits are located "on a belt of serpentine roof pendants that crosses Silver Run Plateau in a northeasterly direction..." north of Lake Fork of Rock Creek (James 1944; Schafer 1937).
James (1944) considered the chromite deposits on the Silver Run Plateau to have "prac-tically no economic possibilities," and their record is poor when compared to those in the neighboring district. Three claims, the Edsel, Four Chromes and Little Nell groups, have proved minor. The only reported production, amounting to 15 tons of ore, came from the Little Nell (James 1944).
Despite the lack of chromite production, the area's only chromite mill was located within the district just east of Red Lodge in Section 27, T7S, R20E. U.S. Vanadium Corporation leased a number of claims in the Hellroaring district in 1941, working them until at least September 1943. The corporation contracted with Stearns-Rogers Corporation for construction of a chrome gravity concentration plant to process ore from the mines. Located on the site of the vacated East Bench coal mine near Red Lodge, the mill was completed in 1942 and had a capacity of 450 tons per day. During its short run from March to November 1942, the mill turned out 11,689 tons of concentrate. The resumption of foreign imports and changes in government regulations, however, forced U.S. Vanadium to close the mill in late 1942. The buildings burned nine years later (Anderson 1983; James 1944).
BOUNDARIES OF THE DISTRICT
The Silver Run district is defined by the location of the claims. James (1944) describes the chromite-bearing belt as extending from Section 36, T8S R18E, near the Lake Fork of Rock Creek, northeast to Section 11, T8S R19E, near the West Fork of Rock Creek. The located claims cluster in a smaller area in the south half of T8S R19E (James 1944). Figure 1 delineates the chromite claims as described by James (1944) within the larger Silver Run district as defined by the AMRB (1994).
HISTORIES OF SELECTED MINES
The Edsel claim is located between Snow and Sheep creeks in Sections 28, 33 and 34 T8S R19E. Intrusive granite has broken up the lenses of high grade ore, rendering them of little economic importance. Operations explored the deposits with two pits (James 1944).
Four Chromes Group
The No. 1 claim in this group was the first discovery of chromite in the Silver Run District, located in 1916 by two men working for J. F. Brophy of Red Lodge. The body of serpentine extends for nearly half a mile through the claims, with widths of up to 100 feet. The associated pods of ore are much smaller, the largest being 20 feet long and 12 feet wide. The Bureau of Mines conducted extensive work on the claims in 1942, and most of the 23 trenches and pits come from this project. The ore is poor grade, with a low chromite content and a high percentage of iron. The claims are found in Sections 21, 28 and 29, T8S, R19E (James 1944).
Little Nell Group
The Little Nell Group is located in Sections 29, 30, and 31, T8S R19E, mostly on the Silver Run Plateau between Chrome and Grass creeks. Operators have removed 15 tons of ore and explored the claims with pits and three adits, but the deposits have proved minor (James 1944).
Abandoned Mine Reclamation Bureau (AMRB)
1994 Mining districts of Montana. Maps 1:100,000 and Map #94-NRIS-129. Compiled and edited by Joel Chavez. Prepared by Montana State Library Natural Resource Information System (NRIS) for Montana Department of State Lands. Helena
1983 Cultural Resources Inventory and Evaluation: Red Lodge East Bench - Washoe - Highway - Burns - Smith Mines. Prepared for Montana Department of State Lands by Cultural Resource Division, GCM Services, Inc., Butte.
Bowman, A. H. and Barclay Craighead
Montana, Resources and Opportunities Edition
, Vol. 3. Department of Agricultural, Labor and Industry, Division of Publicity.
James, H. L.
1944 Chromite Deposits near Red Lodge, Carbon County, Montana.
U.S.G.S. Bulletin 945-F
Schafer, Paul A.
Chromite Deposits of Montana
. Memoir No. 18, Montana School of Mines, Butte.