High Commission Mine (Big Ledge vein; High Commission vein), Downieville, Downieville Mining District, Sierra County, California, USAi
| Regional Level Types | |
|---|---|
| High Commission Mine (Big Ledge vein; High Commission vein) | Mine |
| Downieville | - not defined - |
| Downieville Mining District | Mining District |
| Sierra County | County |
| California | State |
| USA | Country |
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Latitude & Longitude (WGS84):
39° 33' 52'' North , 120° 48' 12'' West
Latitude & Longitude (decimal):
Type:
Köppen climate type:
Nearest Settlements:
| Place | Population | Distance |
|---|---|---|
| Downieville | 282 (2011) | 2.1km |
| Sierra City | 221 (2011) | 14.5km |
| Pike | 134 (2011) | 21.7km |
| Washington | 185 (2011) | 22.8km |
| Plumas Eureka (historical) | 339 (2011) | 23.1km |
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 |
|---|---|---|
| Nevada County Gem & Mineral Society | Grass Valley, California | 44km |
A former lode Au occurrence/mine located in secs. 25 & 26, T20N, R10E, MDM, 2.1 km (1.3 miles) ENE of Downieville, W of New York Ravine and N of the North Yuba River, on National Forest land. MRDS database stated accuracy for this location is 1,000 meters. Intermittent production occurred during the period 1905 to 1914.
Mineralization is a vein deposit hosted in slate, porphyry and quartzite. The ore body strikes N and dips vertically. There are 2 parallel veins, with the High Commission vein at 4½ feet thick and dips nearly vertically with a surface outcrop for 3 miles (4.8 km). It has a slate footwall and a porphyry hanging wall. The Big Ledge vein is an 11 foot thick quartz vein with slate & decomposed porphyry carying free gold and no sulfides. The veins are parallel to the Mexican vein 300 feet E. High grade bunch of arsenopyrite was encountered. Local rocks include Paleozoic marine rocks, undivided, unit 4 (Western Sierra Nevada).
Workings include surface and underground openings with an overall depth of 76.2 meters and an overall length of 1,097.28 meters and comprised of adits, crosscuts at 300 feet total.
Production data are found in: MacBoyle, Errol (1920b).
Select Mineral List Type
Standard Detailed Gallery Strunz Chemical ElementsDetailed Mineral List:
| ⓘ Arsenopyrite Formula: FeAsS |
| ⓘ Native Gold Formula: Au |
| ⓘ Quartz Formula: SiO2 |
Gallery:
List of minerals arranged by Strunz 10th Edition classification
| Group 1 - Elements | |||
|---|---|---|---|
| ⓘ | Native Gold | 1.AA.05 | Au |
| Group 2 - Sulphides and Sulfosalts | |||
| ⓘ | Arsenopyrite | 2.EB.20 | FeAsS |
| Group 4 - Oxides and Hydroxides | |||
| ⓘ | Quartz | 4.DA.05 | SiO2 |
List of minerals for each chemical element
| O | Oxygen | |
|---|---|---|
| O | ⓘ Quartz | SiO2 |
| Si | Silicon | |
| Si | ⓘ Quartz | SiO2 |
| S | Sulfur | |
| S | ⓘ Arsenopyrite | FeAsS |
| Fe | Iron | |
| Fe | ⓘ Arsenopyrite | FeAsS |
| As | Arsenic | |
| As | ⓘ Arsenopyrite | FeAsS |
| Au | Gold | |
| Au | ⓘ Native Gold | Au |
Other Databases
| Link to USGS MRDS: | 10034782 |
|---|
Other Regions, Features and Areas containing this locality
North AmericaContinent
North America PlateTectonic Plate
- Calaveras-Baker DomainDomain
- Sierra Nevada BatholithVolcanic Arc
USA
- Sierra NevadaMountain Range
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References
(n.d.) Minerals Availability System (MAS), U.S. Bureau of Mines.file #0060910293
