| Basis for focus area |
East-west belt of antimony occurrences the Boise Basin- Horseshoe Bend area. |
| Identified resources |
Past production of antimony, gold, lead, and silver. |
| Production |
Entire production of ore from Hermada was 5,000 tons, containing about 640 ton Sb, of which 550 tons were recovered (Popoff, 1953). |
| Status |
Past mining. |
| Estimated resources |
Unknown. |
| Geologic maps |
Anderson (1934), scale 1:48,768; Anderson (1947a), scale 1:24,000; Kiilsgaard and others (2001), scale 1:100,000. |
| Geophysical data |
See McCafferty and Abrams (1991), scale 1:250,000. |
| Favorable rocks and structures |
Boise basin quartz diorite of the Idaho batholith. |
| Deposits |
Hermada Antimony mine (MRDS dep_id: 10070739), Summit mine, Twin Sister mine (MRDS dep_id: 10105548), Clear Creek mine. |
| Evidence from mineral occurrences |
MRDS. |
| Geochemical evidence |
Ore at Mountain Chief mine assayed 0.053 oz Au; arsenopyrite sample assayed 1.36 oz Au, 0.7 oz Ag, 2% Bi, 0.3% Pb and 0.6% Sb; see Malcolm and Smith (1991). |
| Geophysical evidence |
Unknown. |
| Evidence from other sources |
Unknown. |
| Comments |
Because of variable mineralogy related to different stages of metallization, deposits are differentiated into pyritic lodes, base-metal lodes, gold and base-metal lodes, gold-bismuth lodes, gold-quartz lodes, silver-gold lodes, and silver lodes, each of which has certain other distinguishing features of composition (Anderson, 1947a). |
| Cover thickness and description |
Veins exposed at the surface; erosion created local placer deposits. |
| Authors |
Virginia S. Gillerman, Reed S. Lewis, Christopher A. Tate, Jane M. Hammarstrom. |
| New data needs |
Geophysics, good regional mapping exists; mine-scale work stopped in the 1950s but could be added to. |
| Geologic mapping and modeling needs |
1:24,000 scale geologic mapping in progress (STATEMAP). |
| Geophysical survey and modeling needs |
High resolution, Rank 1 aeromagnetic and aeroradiometric coverage. |
| Digital elevation data needs |
Lidar mostly complete; some areas in progress, small area incomplete. |
