| Basis for focus area |
Outline of placer localities in MRDS with PGE production listed by Peterson (1994); localities may not be exact. |
| Identified resources |
Historical production of gold and PGE. |
| Production |
Folsom placer produced about 5,000 oz PGE. |
| Status |
Past placer mining. |
| Estimated resources |
Unknown. |
| Geologic maps |
Bartow and Helley (1979), scale 1:62,500. |
| Geophysical data |
Inadequate aeromagnetic and aeroradiometric coverage. |
| Favorable rocks and structures |
Gravels in or along the American River and near the lower contacts of the Laguna and Mehrten Formations. |
| Deposits |
Folsom placer (MRDS dep_id: 10103627). |
| Evidence from mineral occurrences |
MRDS. |
| Geochemical evidence |
No data. |
| Geophysical evidence |
Unknown. |
| Evidence from other sources |
None. |
| Comments |
Reworking of historical tailings, especially if coupled with mercury cleanup, could provide potential PGE resources if technology and economic incentives warranted the effort. |
| Cover thickness and description |
Surface alluvial/tailings deposits. |
| Authors |
Jane M. Hammarstrom, Erica Key. |
| New data needs |
Updated geologic mapping, lidar, geochemistry, aeromagnetic and aeroradiometric surveys. |
| Geologic mapping and modeling needs |
Updated geologic mapping. |
| Geophysical survey and modeling needs |
High-resolution, Rank 1 aeromagnetic and aeroradiometric surveys. |
| Digital elevation data needs |
Lidar complete for northern half of focus area, in progress for southern half. |
