Dewey's Mine, Black Oaks, West Mayacmas Mining District, Sonoma County, California, USAi
| Regional Level Types | |
|---|---|
| Dewey's Mine | Mine |
| Black Oaks | Town |
| West Mayacmas Mining District | Mining District |
| Sonoma County | County |
| California | State |
| USA | Country |
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Latitude & Longitude (WGS84):
38° 47' 53'' North , 122° 49' 41'' West
Latitude & Longitude (decimal):
Type:
Köppen climate type:
Nearest Settlements:
| Place | Population | Distance |
|---|---|---|
| Cobb | 1,778 (2011) | 9.5km |
| Geyserville | 862 (2011) | 12.0km |
| Cloverdale | 8,811 (2017) | 16.4km |
| Middletown | 1,323 (2011) | 19.2km |
| Clear Lake Riviera | 3,090 (2017) | 19.6km |
Nearest Clubs:
Local clubs are the best way to get access to collecting localities
Local clubs are the best way to get access to collecting localities
| Club | Location | Distance |
|---|---|---|
| Santa Rosa Mineral And Gem Society, Inc. | Santa Rosa, California | 41km |
Other/historical names associated with this locality:
Wild Hog Mine; Cima Mine; Big Red Mine; Dewey Mine; Eagle Rock Mine
Production data are found in: U.S. Bureau of Mines file data.
The Wild Hog, Eagle Rock, Big Red, and Cima workings, in sec. 14, T. 11 N., R. 9 W., had been leased in 1944 by Frank A. Dewey from The Geysers Development Company. The properties lie along a north-west-trending zone on the south side of the Cloverdale-Geysers road. Prior to 1944 the ore from the workings had been reported, but in that year a rotary furnace of about 20 tons daily capacity was being installed. Prospecting in the area began in 1940 or 1941, and the mine is still in the development stage, but it has yielded almost 100 flasks from reports.
The workings consist of several short adits, totaling about 600 feet, and small open cuts scattered over an area about 4000 feet long. These workings lie on the northern edge of a wide shear zone intruded by thin lenses of serpentine, which is altered in places to silica-carbonate rock. Cinnabar and a little native mercury have been found at several places in the sandstone near the serpentine, and smaller quantities of both have been found in the silica-carbonate rock. The ore bodies so far encountered have been small, but so rich and so closely spaced as to encourage further prospecting and development.
The workings consist of several short adits, totaling about 600 feet, and small open cuts scattered over an area about 4000 feet long. These workings lie on the northern edge of a wide shear zone intruded by thin lenses of serpentine, which is altered in places to silica-carbonate rock. Cinnabar and a little native mercury have been found at several places in the sandstone near the serpentine, and smaller quantities of both have been found in the silica-carbonate rock. The ore bodies so far encountered have been small, but so rich and so closely spaced as to encourage further prospecting and development.
Select Mineral List Type
Standard Detailed Gallery Strunz Chemical ElementsCommodity List
This is a list of exploitable or exploited mineral commodities recorded at this locality.Mineral List
2 valid minerals.
Rock Types Recorded
Note: data is currently VERY limited. Please bear with us while we work towards adding this information!
Select Rock List Type
Alphabetical List Tree DiagramDetailed Mineral List:
| ⓘ Cinnabar Formula: HgS |
| ⓘ Native Mercury Formula: Hg |
List of minerals arranged by Strunz 10th Edition classification
| Group 1 - Elements | |||
|---|---|---|---|
| ⓘ | Native Mercury | 1.AD.05 | Hg |
| Group 2 - Sulphides and Sulfosalts | |||
| ⓘ | Cinnabar | 2.CD.15a | HgS |
List of minerals for each chemical element
| S | Sulfur | |
|---|---|---|
| S | ⓘ Cinnabar | HgS |
| Hg | Mercury | |
| Hg | ⓘ Cinnabar | HgS |
| Hg | ⓘ Native Mercury | Hg |
Other Databases
| Link to USGS MRDS: | 10040825 |
|---|
Other Regions, Features and Areas containing this locality
North AmericaContinent
- Coast MountainsMountain Range
North America PlateTectonic Plate
- California Coast RangesAccretionary Complex
- Franciscan DomainDomain
USA
- California
- Mayacamas MountainsMountain Range
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Dewey's Mine, Black Oaks, West Mayacmas Mining District, Sonoma County, California, USA