Fortner Ranch prospect (Fortner Ranch property), San Andreas area, Calaveras County, California, USAi
| Regional Level Types | |
|---|---|
| Fortner Ranch prospect (Fortner Ranch property) | Prospect |
| San Andreas area | Area |
| Calaveras County | County |
| California | State |
| USA | Country |
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Latitude & Longitude (WGS84):
38° 13' 33'' North , 120° 39' 47'' West
Latitude & Longitude (decimal):
Type:
Köppen climate type:
Nearest Settlements:
| Place | Population | Distance |
|---|---|---|
| San Andreas | 2,783 (2011) | 3.6km |
| Mokelumne Hill | 646 (2011) | 9.1km |
| Mountain Ranch | 1,628 (2011) | 10.7km |
| Valley Springs | 3,553 (2011) | 15.0km |
| Jackson | 4,649 (2017) | 16.8km |
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 | 21km |
| Amador County Gem & Mineral Society | Sutter Creek, California | 22km |
A Mn occurrence located in the SW¼ sec. 4, T4N, R12E, MDM, about 4 km NNE of San Andreas, along the North Fork Murray Creek (on crest of a ridge 0.3 mile SE of the road). MRDS database stated accuracy for this location is 100 meters.
The ore body strikes N40-55W and dips nearly vertical. The Mn is chiefly in the form of partly oxidized brown manganese garnet, spessartine, occurring in a bed of massive metachert. The metachert has been recrystallized to fine-grained gray quartzite, and is cut by quartz veins up to 3 feet (0.91 meter) thick. The general strike is as stated above. The belt of metachert extends along the strike for at least 450 feet. The spessartine is coated with black Mn oxides - pyrolusite and psilomelane. Local rocks include Paleozoic marine rocks, undivided, unit 4 (Western Sierra Nevada).
Workings include surface openings. One pit is 6 feet by 6 feet by 6 feet; a second is 350 feet to the NW and is 2 feet by 2 feet by 2 feet. Two additional pits are located 100 feet NW of pit No. 2.
Select Mineral List Type
Standard Detailed Gallery Strunz Chemical ElementsDetailed Mineral List:
| ⓘ 'Psilomelane' |
| ⓘ Pyrolusite Formula: Mn4+O2 |
| ⓘ Spessartine Formula: Mn2+3Al2(SiO4)3 |
Gallery:
List of minerals arranged by Strunz 10th Edition classification
| Group 4 - Oxides and Hydroxides | |||
|---|---|---|---|
| ⓘ | Pyrolusite | 4.DB.05 | Mn4+O2 |
| Group 9 - Silicates | |||
| ⓘ | Spessartine | 9.AD.25 | Mn2+3Al2(SiO4)3 |
| Unclassified | |||
| ⓘ | 'Psilomelane' | - | |
List of minerals for each chemical element
| O | Oxygen | |
|---|---|---|
| O | ⓘ Pyrolusite | Mn4+O2 |
| O | ⓘ Spessartine | Mn32+Al2(SiO4)3 |
| Al | Aluminium | |
| Al | ⓘ Spessartine | Mn32+Al2(SiO4)3 |
| Si | Silicon | |
| Si | ⓘ Spessartine | Mn32+Al2(SiO4)3 |
| Mn | Manganese | |
| Mn | ⓘ Pyrolusite | Mn4+O2 |
| Mn | ⓘ Spessartine | Mn32+Al2(SiO4)3 |
Other Databases
| Link to USGS MRDS: | 10028845 |
|---|
Other Regions, Features and Areas containing this locality
North AmericaContinent
North America PlateTectonic Plate
- Shoofly-Olds Ferry DomainDomain
- Sierra Nevada BatholithVolcanic Arc
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