| Basis for focus area |
Multi-part focus area of bismuth-bearing polymetallic Pb-Ag and Au-Ag veins, replacements, and mineralized shear zones. Main area includes Washington Basin. |
| Identified resources |
Possible identified resources of bismuth in gold and silver mineralization; historical production of gold, lead, and silver. |
| Production |
Unknown. |
| Status |
Past mining. |
| Estimated resources |
Inferred submarginal Au-Ag veins (Empire and Washington) estimated at about 5,000,000 tons (4,500,000 tonnes); semi-quantitative analyses assays of vary from 0. 05 to 0.07% Bi. An additional l,600,000 tons (1,450,000 tonnes) of submarginal material from the nearby Last Resort vein may average 0.30% Bi (Tschanz and Kiilsgaard, 1986). |
| Geologic maps |
Tschanz and others (1986, plate 1), scale 1:62,500; Rember and Bennett (1979), scale 1:250,000. |
| Geophysical data |
Inadequate aeromagnetic and aeroradiometric coverage. |
| Favorable rocks and structures |
In the Washington basin, polymetallic vein deposits near the Cretaceous granodiorite-Paleozoic contact and in fold-hinge parallel fractures are interpreted to be the result of late-stage hydrothermal fluid circulation associated with intrusion of Cretaceous granodiorite (Mahoney, 1995). |
| Deposits |
Last Resort vein (MRDS dep_id: 10070967), Reconstruction vein (MRDS dep_id: 10071213), Yacomella veins (MRDS dep_id: 10071212), Empire vein (Washington Basin deposit) (MRDS dep_id: 10096298). |
| Evidence from mineral occurrences |
MRDS. |
| Geochemical evidence |
Anomalous Bi in rocks, streambed sediments, and soils in the Washington Basin area. Minerals: bismuthinite, native bismuth, bismuth tellurides, tetradymite, joséite (Tschanz and Kiilsgaard, 1986). |
| Geophysical evidence |
Unknown. |
| Evidence from other sources |
Unknown. |
| Comments |
Claims in the Washington Basin were originally located for Au, but most production was in Pb-Ag ores and some interest has been shown in the scheelite and telluride occurrences (Tschanz and Kiilsgaard, 1986). |
| Cover thickness and description |
Exposed at the surface. |
| Authors |
Reed S. Lewis, Virginia S. Gillerman, Christopher A. Tate, Jane M. Hammarstrom. |
| New data needs |
Geophysics. |
| Geologic mapping and modeling needs |
None requested at this time. |
| Geophysical survey and modeling needs |
High-resolution, Rank 1 aeromagnetic and aeroradiometric surveys. |
| Digital elevation data needs |
Lidar incomplete. |
