Alhambra Gold Mine (Alhambra Mine; Atlantic Mine), Spanish Flat, Spanish Flat Mining District, East Belt, El Dorado County, California, USAi
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Latitude & Longitude (WGS84):
38° 49' 31'' North , 120° 47' 24'' West
Latitude & Longitude (decimal):
Type:
Köppen climate type:
Nearest Settlements:
| Place | Population | Distance |
|---|---|---|
| Coloma | 529 (2011) | 9.1km |
| Georgetown | 2,367 (2011) | 10.0km |
| Placerville | 10,650 (2017) | 10.7km |
| Cold Springs | 446 (2011) | 11.6km |
| Camino | 1,750 (2011) | 13.9km |
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 |
|---|---|---|
| El Dorado County Mineral and Gem Society | Placerville, California | 11km |
| Gold Country Treasure Seekers | Placerville, California | 11km |
| Roseville Rock Rollers | Roseville, California | 44km |
| Amador County Gem & Mineral Society | Sutter Creek, California | 48km |
| Nevada County Gem & Mineral Society | Grass Valley, California | 50km |
A former lode Au occurrence/mine located in secs. 6 & 7 (center of common sections boundary), T11N, R11E, MDM, 1.7 km (1.1 miles) E of Spanish Flat (on the S side of Round Hill; 6 miles SSE of Georgetown), on private land. Operated in 1883, 1886, 1890, 1934 to 1942 and 1947. MRDS database stated accuracy for this location is 100 meters.
Mineralization is a vein deposit hosted in rocks of the Mariposa Formation (schist, amphibolite, slate). The ore body is pod-like bodies, strikes N50W and dips NE. The ore shoot at the fault is lensoidal and plunged to the SE. Deposit is located near the E margin of the belt of mariposa slate. The vein is in a fault zone and consists of strings of pod-like bodies of quartz in chlorite-sericite schist. Several smaller parallel veins occur in the hanging wall. The main hanging wall is amphibolite schist while the footwall is graphitic-sericite schist and slate. Calcite and schistose dikes are associated with the vein. Controls for ore emplacement included junctions of the fault favorable for localization of ore and maybe a conduit for gold-bearing solutions. Local rocks include Paleozoic marine rocks, undivided, unit 4 (Western Sierra Nevada).
Workings include underground openings comprised of a 440 foot inclined shaft with a 75 foot shaft 600 feet to the SE. There are 3,000 feet of drifts and crosscuts with main levels at 125, 225, and 400 feet. A winze on the 400 foot level descends to the ore shoot on the 485 foot sub-level.
Local geologic structures include a fault East of the main shaft that splits into 2 branches that generally strike to the NW.
Production data are found in: Clark, Wm. B. & D.W. Carlson (1956).
Two high-grade pockets were encountered in 1934 at 90 feet, and a large pocket in 1939 between the 225 and 275 foot level worth approximately $550,000 (period values). Another high-grade ore pocket was found in 1949 and yielded 324 ounces of Au. At least 50% of the output of the mine was from high-grade ore.
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
6 valid minerals.
Detailed Mineral List:
| ⓘ Calcite Formula: CaCO3 |
| ⓘ 'Chlorite Group' Description: Occurs in chlorite-sericite schist. |
| ⓘ Graphite Formula: C Description: Occurs in graphitic-sericitic schist. |
| ⓘ Muscovite Formula: KAl2(AlSi3O10)(OH)2 Description: Occurs in chlorite-sericite and graphitic-sericitic schists. |
| ⓘ Muscovite var. Sericite Formula: KAl2(AlSi3O10)(OH)2 Description: Occurs in chlorite-sericite and graphitic-sericitic schists. |
| ⓘ Native Gold Formula: Au |
| ⓘ Pyrite Formula: FeS2 |
| ⓘ Quartz Formula: SiO2 |
Gallery:
List of minerals arranged by Strunz 10th Edition classification
| Group 1 - Elements | |||
|---|---|---|---|
| ⓘ | Native Gold | 1.AA.05 | Au |
| ⓘ | Graphite | 1.CB.05a | C |
| Group 2 - Sulphides and Sulfosalts | |||
| ⓘ | Pyrite | 2.EB.05a | FeS2 |
| Group 4 - Oxides and Hydroxides | |||
| ⓘ | Quartz | 4.DA.05 | SiO2 |
| Group 5 - Nitrates and Carbonates | |||
| ⓘ | Calcite | 5.AB.05 | CaCO3 |
| Group 9 - Silicates | |||
| ⓘ | Muscovite | 9.EC.15 | KAl2(AlSi3O10)(OH)2 |
| ⓘ | var. Sericite | 9.EC.15 | KAl2(AlSi3O10)(OH)2 |
| Unclassified | |||
| ⓘ | 'Chlorite Group' | - | |
List of minerals for each chemical element
| H | Hydrogen | |
|---|---|---|
| H | ⓘ Muscovite | KAl2(AlSi3O10)(OH)2 |
| H | ⓘ Muscovite var. Sericite | KAl2(AlSi3O10)(OH)2 |
| C | Carbon | |
| C | ⓘ Calcite | CaCO3 |
| C | ⓘ Graphite | C |
| O | Oxygen | |
| O | ⓘ Calcite | CaCO3 |
| O | ⓘ Muscovite | KAl2(AlSi3O10)(OH)2 |
| O | ⓘ Quartz | SiO2 |
| O | ⓘ Muscovite var. Sericite | KAl2(AlSi3O10)(OH)2 |
| Al | Aluminium | |
| Al | ⓘ Muscovite | KAl2(AlSi3O10)(OH)2 |
| Al | ⓘ Muscovite var. Sericite | KAl2(AlSi3O10)(OH)2 |
| Si | Silicon | |
| Si | ⓘ Muscovite | KAl2(AlSi3O10)(OH)2 |
| Si | ⓘ Quartz | SiO2 |
| Si | ⓘ Muscovite var. Sericite | KAl2(AlSi3O10)(OH)2 |
| S | Sulfur | |
| S | ⓘ Pyrite | FeS2 |
| K | Potassium | |
| K | ⓘ Muscovite | KAl2(AlSi3O10)(OH)2 |
| K | ⓘ Muscovite var. Sericite | KAl2(AlSi3O10)(OH)2 |
| Ca | Calcium | |
| Ca | ⓘ Calcite | CaCO3 |
| Fe | Iron | |
| Fe | ⓘ Pyrite | FeS2 |
| Au | Gold | |
| Au | ⓘ Native Gold | Au |
Other Databases
| Link to USGS MRDS: | 10007088 |
|---|
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 #0060170825
