| Basis for focus area |
Tungsten placer district outline from USMIN location polygon CA00061. |
| Identified resources |
Historical production of gold and tungsten. |
| Production |
Alitolia district (1906-1939): Approximately 821,000 units of tungsten trioxide (WO3), equivalent to 13,683 tons of concentrates containing 60% WO3 produced from the district (Lemmon and Dorr, 1940). Of this total, 94% came from veins and 6% from placers. |
| Status |
Past mining. |
| Estimated resources |
Mill tailings contain an appreciable reserve, and are now being re-treated. Placer deposits contain possibly 28,000,000 cubic yards estimated to average more than a quarter of a pound of scheelite per cubic yard, or a total of at least 280,000 units of WO3 (Lemmon and Dorr, 1940). Certain parts of the placers contain sufficient scheelite to be workable at normal prices, and discovery of methods by which the gold content could be recovered might permit production of scheelite as a byproduct from the submarginal placers. |
| Geologic maps |
Lemmon and Dorr (1940), scale 1:4,800. |
| Geophysical data |
Inadequate aeromagnetic and aeroradiometric coverage. |
| Favorable rocks and structures |
High-grade scheelite ore, with a quartz-carbonate gangue, has been mined in the Atolia mining district from steeply dipping fissure veins of Miocene age. A minor quantity of scheelite has been taken from placers. The country rock is quartz monzonite probably of late Jurassic age. |
| Deposits |
Atolia-Rand placers (MRDS dep_id: 10035311; USMIN Site_ID: CA00061). |
| Evidence from mineral occurrences |
MRDS; USMIN. |
| Geochemical evidence |
Scheelite is the only ore mineral and occurs in veins and stream placers. |
| Geophysical evidence |
Unknown. |
| Evidence from other sources |
Unknown. |
| Comments |
High-grade scheelite ore, with a quartz-carbonate gangue, has been mined in the Atolia mining district from steeply dipping fissure veins of Miocene age. A minor quantity of scheelite has been taken from placers. The country rock is quartz monzonite probably of late Jurassic age. |
| Cover thickness and description |
Exposed at the surface. |
| Authors |
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 inadequate. |
