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North Fork Chrome Mine, Snakehead Point, Placer County, California, USAi
| Regional Level Types | |
|---|---|
| North Fork Chrome Mine | Mine |
| Snakehead Point | Point |
| Placer County | County |
| California | State |
| USA | Country |
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Latitude & Longitude (WGS84):
39° 9' 41'' North , 120° 47' 10'' West
Latitude & Longitude (decimal):
Type:
Köppen climate type:
Nearest Settlements:
| Place | Population | Distance |
|---|---|---|
| Alta | 610 (2011) | 5.5km |
| Dutch Flat | 160 (2011) | 6.7km |
| Colfax | 2,005 (2017) | 15.9km |
| Foresthill | 1,483 (2011) | 15.9km |
| Washington | 185 (2011) | 22.0km |
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 |
|---|---|---|
| Nevada County Gem & Mineral Society | Grass Valley, California | 25km |
| El Dorado County Mineral and Gem Society | Placerville, California | 48km |
| Gold Country Treasure Seekers | Placerville, California | 48km |
A former Cr-Fe occurrence/mine located in sec. 7, T15N, R11E, MDM, 1.6 km (1.0 mile) SSW of Snakehead Point (coordinates of record), on the divide between Giant Gap Gulch on the W and McIntyre Gulch on the E, on a private lease on National Forest land. Discovered in 1917. First operated in 1918. First production occurred in 1940. First production figure was mined in 1918 but not shipped until 1940. Operated by C. H. and H. A. Geisendorfer (last operators in 1940), California. MRDS database stated accuracy for this location is 10 meters. This mine is located on a steep E-facing slope of N-trending ridge of the Iowa Hill Divide.
This is one of many Cr deposits/mines placed into a very large area termed the "Forest Hill Divide area" by Rynearson. That area is based on geological and topographic considerations versus mining districts and overlaps several defined districts. Those Cr occurrences within mining districts are listed under their respective districts, the remainder are listed under Rynearson’s "Forest Hill Divide area."
Mineralization is hosted in dunite. The ore body is disseminated, irregular in form. The primary mode of origin was magmatic differentiation and primary ore control was lithology and the secondary control being fracturing. Wallrock alteration is intense (carbonitization). Local alteration involved the complete serpentinization of dunite. This deposit is situated in a linear mass of ultramafic rocks that has intruded a sequence of Paleozoic metamorphics of the Calaveras group. The eastern contact of the ultramafics is co-linear with, and probably part of, the Melones Fault Zone. Local rocks include ultramafic rocks, chiefly Mesozoic, unit 2 (Western Sierra Nevada and Klamath Mountains).
Local geologic structures: Two prominent sets of joints fracture the peridotite rock mass into roughly rectangular boulders.
Workings include surface openings comprised of an open cut 15 feet long and 15 feet deep (1953). All workings were obliterated by a bulldozer as of 1975.
Production data are found in: Rynearson, Garn Arthur (1953).
Analysis of 113 long tons of ore in 1941 gave 46.64% Cr2O3 with Cr:Fe 2.6. The deposit contained between 20-60% Cr2O3.
Select Mineral List Type
Standard Detailed Gallery Strunz Chemical ElementsDetailed Mineral List:
| ⓘ Chromite Formula: Fe2+Cr3+2O4 |
| ⓘ 'Fayalite-Forsterite Series' |
| ⓘ 'Pyroxene Group' Formula: ADSi2O6 |
| ⓘ 'Serpentine Subgroup' Formula: D3[Si2O5](OH)4 |
Gallery:
List of minerals arranged by Strunz 10th Edition classification
| Group 4 - Oxides and Hydroxides | |||
|---|---|---|---|
| ⓘ | Chromite | 4.BB.05 | Fe2+Cr3+2O4 |
| Unclassified | |||
| ⓘ | 'Fayalite-Forsterite Series' | - | |
| ⓘ | 'Pyroxene Group' | - | ADSi2O6 |
| ⓘ | 'Serpentine Subgroup' | - | D3[Si2O5](OH)4 |
List of minerals for each chemical element
| H | Hydrogen | |
|---|---|---|
| H | ⓘ Serpentine Subgroup | D3[Si2O5](OH)4 |
| O | Oxygen | |
| O | ⓘ Chromite | Fe2+Cr23+O4 |
| O | ⓘ Fayalite-Forsterite Series | |
| O | ⓘ Pyroxene Group | ADSi2O6 |
| O | ⓘ Serpentine Subgroup | D3[Si2O5](OH)4 |
| Mg | Magnesium | |
| Mg | ⓘ Fayalite-Forsterite Series | |
| Si | Silicon | |
| Si | ⓘ Fayalite-Forsterite Series | |
| Si | ⓘ Pyroxene Group | ADSi2O6 |
| Si | ⓘ Serpentine Subgroup | D3[Si2O5](OH)4 |
| Cr | Chromium | |
| Cr | ⓘ Chromite | Fe2+Cr23+O4 |
| Fe | Iron | |
| Fe | ⓘ Chromite | Fe2+Cr23+O4 |
| Fe | ⓘ Fayalite-Forsterite Series | |
Other Databases
| Link to USGS MRDS: | 10043717 |
|---|
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 #0060610631
