Bachman Mine (Backman Mine), Fourth Crossing, San Andreas Mining District, Calaveras County, California, USAi
| Regional Level Types | |
|---|---|
| Bachman Mine (Backman Mine) | Mine |
| Fourth Crossing | Unincorporated Community |
| San Andreas Mining District | Mining District |
| Calaveras County | County |
| California | State |
| USA | Country |
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Latitude & Longitude (WGS84):
38° 7' 40'' North , 120° 37' 43'' West
Latitude & Longitude (decimal):
Type:
Köppen climate type:
Nearest Settlements:
| Place | Population | Distance |
|---|---|---|
| San Andreas | 2,783 (2011) | 8.8km |
| Angels Camp | 2,677 (2012) | 10.2km |
| Mountain Ranch | 1,628 (2011) | 13.6km |
| Vallecito | 442 (2011) | 14.2km |
| Murphys | 2,213 (2015) | 14.7km |
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 |
|---|---|---|
| Calaveras Gem & Mineral Society | Angels Camp, California | 10km |
| Amador County Gem & Mineral Society | Sutter Creek, California | 33km |
A former lode Au mine located in the NE¼NE¼ sec. 10 and in the SW¼NW¼ sec. 11, T3N, R12E, MDM, 0.7 km (0.4 mile) SE of Fourth Crossing, between the Dutch Ed Gulch and California highway 49 (7 miles S of San Andreas; near the San Andreas and Angels Road). Operated during the periods 1894 to 1914, 1921, and active intermittently in the 1920's and 1930's. MRDS database stated accuracy for this location is 100 meters.
Mineralization is a vein deposit hosted in greenstone and slate. The ore body strikes NW and dips E at a width of 1.68 meters. The hanging wall is comprised of interbedded slate and schist. The footwall is greenstone. A fault at 285 feet of depth has a N & W displacement of the vein. There are 2 main veins, one running NW, the other E. They converge to the N. Several other veins run from the Thorpe Mine into the Bachman. Local rocks include undivided pre-Cenozoic metavolcanic rocks, unit 2 (undivided).
Local geologic structures include small faults which offset the vein(s).
Workings include underground openings with an overall depth of 145.69 meters and comprised of several shafts at 70, 305 & 478 feet deep, respectively. The 305 foot shaft has a 75 degree angle with levels at 110 and 285 feet, with drifts and crosscuts.
Production data are found in: Clark, Wm. B. & P.A. Lydon (1962).
Analytical data results: Assayed low on the 110 foot level. Good assays were reported near the face of the SE drift on the 285 level.
No production record was found. The ore was free-milling. The ore in 1921 paid well.
Select Mineral List Type
Standard Detailed Gallery Strunz Chemical ElementsDetailed Mineral List:
| ⓘ 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 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 |
| Au | Gold | |
| Au | ⓘ Native Gold | Au |
Other Databases
| Link to USGS MRDS: | 10102640 |
|---|
Other Regions, Features and Areas containing this locality
North AmericaContinent
North America PlateTectonic Plate
- Calaveras-Baker DomainDomain
- Sierra Nevada BatholithVolcanic Arc
USA
- California
- Mother Lode BeltBelt
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References
(n.d.) Minerals Availability System (MAS), U.S. Bureau of Mines.file ID #0060090342
Clark, Lorin D. (1954) Geology and mineral deposits of the Calaveritas quadrangle, Calaveras County, California. Special Report 40. California Division of Mines p.20
