| Basis for focus area |
Description of Red Lodge chromite district by Simons and others (1979), prior production. |
| Identified resources |
Identified resources and historical production of chromium (chromite). |
| Production |
43,800 tons chromite ore mined from the Hellroaring Group and 24,000 tons from the Highline Group in the 1940s (Simons and others, 1979). |
| Status |
Past mining; no current mining or exploration. |
| Estimated resources |
Some chromite-bearing lenses completely mined out; ~77,000 tons of chromite ore containing 12.8% Cr2O3 is estimated to remain (Simons and others, 1979). |
| Geologic maps |
Lopez (2001), scale 1:100,000. |
| Geophysical data |
Inadequate aeromagnetic and aeroradiometric coverage. |
| Favorable rocks and structures |
Chromite-bearing lenses of serpentinized ultramafic rocks. |
| Deposits |
Highline group (MRDS dep_id: 10221207), Gallon Jug No. 4 (MRDS dep_id: 10148891), North Star claim (MRDS dep_id: 10220476), Little Nell group (MRDS dep_id: 10269888). |
| Evidence from mineral occurrences |
MRDS; Simons and others (1979). |
| Geochemical evidence |
Stream-sediment analyses in Simons and others (1979). |
| Geophysical evidence |
Unknown. |
| Evidence from other sources |
Chromite-bearing serpentine found at the surface, guide for prospecting. |
| Comments |
Relatively small and low-grade deposits compared to nearby Stillwater Complex. PGE, cobalt, and nickel deemed sub-economic (Loferski, 1986). |
| Cover thickness and description |
Exposed at the surface. |
| Authors |
Jane M. Hammarstrom, Jay A. Gunderson. |
| New data needs |
Compilation and integration of data from lidar, airborne geophysics, outcrop maps, and underground workings, lidar. |
| Geologic mapping and modeling needs |
Document and map marker beds; look for evidence for out-of-geochronology-sequence map units; 3D modeling of layers and structure. |
| Geophysical survey and modeling needs |
High resolution airborne surveys where magmatic unconformities are suspected. |
| Digital elevation data needs |
Lidar complete only over northeast section of focus area; incomplete elsewhere. |
