Duncan Mine (Lost Douglas Mine), Hornitos, Hornitos Mining District, West Belt, Mariposa County, California, USAi
| Regional Level Types | |
|---|---|
| Duncan Mine (Lost Douglas Mine) | Mine |
| Hornitos | - not defined - |
| Hornitos Mining District | Mining District |
| West Belt | - not defined - |
| Mariposa County | County |
| California | State |
| USA | Country |
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Latitude & Longitude (WGS84):
37° 29' 27'' North , 120° 12' 57'' West
Latitude & Longitude (decimal):
Type:
Köppen climate type:
Nearest Settlements:
| Place | Population | Distance |
|---|---|---|
| Bear Valley | 125 (2011) | 12.1km |
| Catheys Valley | 825 (2011) | 12.3km |
| Snelling | 231 (2011) | 19.8km |
| Mariposa | 2,173 (2017) | 22.0km |
| Planada | 4,584 (2011) | 24.0km |
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 |
|---|---|---|
| Mariposa Gem & Mineral Club | Mariposa, California | 22km |
A former lode Au-Ag mine located in secs. 16 & 21, T5S, R16E, MDM, 2.3 km (7,500 feet) SE of Hornitos, in the fork at the confluence of Eldorado Creek and Givens Gulch, on private land. Discovered before 1870. Property consists of 1 patented claim. Operated 1897-1898, 1927 and 1932-1935. Operated by George D. Turner. MRDS database stated accuracy for this location is 1,000 meters.
Mineralization is a vein deposit with a vein 2 to 5 feet thick at surface, hosted in greenstone, schist and Late Jurassic hornfels. The ore body is pinch & swell in form, strikes N50W, dips 45NE at a thickness of 1.52 meters. The wall rocks are schistose greenstone, quartz biotite schist and quartz biotite hornfels. Ore is in a vein, pockets and ore shoots. This mine is noted for its pockety character. Local rocks include Jurassic marine rocks, unit 1 (Western Sierra Nevada and Western Klamath Mountains).
Workings include surface and underground openings with an overall length of 777.24 meters and are comprised of a series of open pits and caved shafts strung out along the vein for nearly ½ mile. The main shaft was 325 feet deep in 1935.
Production data are found in: Bowen, O.E., Jr. & C.H. Gray, Jr. (1957).
Production records are incomplete. In 1897-1898, 246 ounces of Au were recoverd from an unknown quantity of ore. In 1927, 500 tons of ore yielded 219.82 ounces of Au and 70 ounces of Ag. From 1932-1935, 1,146 tons of ore yielded 90 ounes of Au and 45 ounces Ag. Idle since the late 1930's. No equipment on the property.
The last ore milled was of marginal grade.
Select Mineral List Type
Standard Detailed Gallery Strunz Chemical ElementsDetailed Mineral List:
| ⓘ Gold Formula: Au |
| ⓘ 'Limonite' Description: pseudomorphs after pyrite in the vein quartz References: |
| ⓘ Pyrite Formula: FeS2 |
| ⓘ Quartz Formula: SiO2 References: |
| ⓘ Silver ? Formula: Ag Description: (Probably refers to the silver content in the native gold, not to the presence of the discrete species "native silver".) |
Gallery:
List of minerals arranged by Strunz 10th Edition classification
| Group 1 - Elements | |||
|---|---|---|---|
| ⓘ | Gold | 1.AA.05 | Au |
| ⓘ | Silver ? | 1.AA.05 | Ag |
| Group 2 - Sulphides and Sulfosalts | |||
| ⓘ | Pyrite | 2.EB.05a | FeS2 |
| Group 4 - Oxides and Hydroxides | |||
| ⓘ | Quartz | 4.DA.05 | SiO2 |
| Unclassified | |||
| ⓘ | 'Limonite' | - | |
List of minerals for each chemical element
| O | Oxygen | |
|---|---|---|
| O | ⓘ Quartz | SiO2 |
| Si | Silicon | |
| Si | ⓘ Quartz | SiO2 |
| S | Sulfur | |
| S | ⓘ Pyrite | FeS2 |
| Fe | Iron | |
| Fe | ⓘ Pyrite | FeS2 |
| Ag | Silver | |
| Ag | ⓘ Silver | Ag |
| Au | Gold | |
| Au | ⓘ Gold | Au |
Other Databases
| Link to USGS MRDS: | 10030938 |
|---|
Other Regions, Features and Areas containing this locality
North AmericaContinent
North America PlateTectonic Plate
- Foothills-Wallowa DomainDomain
- Sierra Nevada BatholithVolcanic Arc
USA
- California
- Mother Lode BeltBelt
- Sierra NevadaMountain Range
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References
(n.d.) Minerals Availability System (MAS), U.S. Bureau of Mines.file ID #0060430189
