Madrid Mine (True Blue Mine; Genochio Mine; Medrid Mine), Murphys, Murphys Mining District (Esmeralda Mining District; Sperry Mining District), East Belt, Calaveras County, California, USAi
| Regional Level Types | |
|---|---|
| Madrid Mine (True Blue Mine; Genochio Mine; Medrid Mine) | Mine |
| Murphys | - not defined - |
| Murphys Mining District (Esmeralda Mining District; Sperry Mining District) | Mining District |
| East Belt | - not defined - |
| Calaveras County | County |
| California | State |
| USA | Country |
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Latitude & Longitude (WGS84):
38° 8' 35'' North , 120° 30' 43'' West
Latitude & Longitude (decimal):
Type:
Köppen climate type:
Nearest Settlements:
| Place | Population | Distance |
|---|---|---|
| Murphys | 2,213 (2015) | 4.5km |
| Vallecito | 442 (2011) | 6.8km |
| Angels Camp | 2,677 (2012) | 8.7km |
| Forest Meadows | 1,249 (2015) | 9.6km |
| Mountain Ranch | 1,628 (2011) | 9.8km |
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 | 9km |
| Amador County Gem & Mineral Society | Sutter Creek, California | 38km |
Mindat Locality ID:
75545
Long-form identifier:
mindat:1:2:75545:9
GUID (UUID V4):
a1fbbe37-d40f-4854-8484-9e922fb7744a
A former Cr-Fe mine located in the SW¼ sec. 2, T3N, R13E, MDM, 2.4 km (7,900 feet) SW of Murphys and about 10 miles NE of Angels Camp (½ mile S of San Domingo Creek at an elevation of about 2,000 feet), on private land. This mine is on the NE side of Ponderosa Way in the SW¼NE¼ of the section (Special Report 40: 21). Discovered in 1916. First operated in 1917. Owned by M. S. Shepard, C/O S. Murphy, San Mateo, California (1975). Operated by A. Genochio (1943). MRDS database stated accuracy for this location is 10 or 1,000 meters (2 MRDS files).
NOTE: Pemberton presents the mine name as "Medrid."
The ore body strikes N80W and dips 65S at a thickness of 3.7 meters, and with a width of 5 meters, a length of 30 meters. Ore body No. 1 is tabular, disseminated. Ore body No. 2 is irregular and ore body No. 3 is lenticular. The primary mode of origin was magmatic differentiation. Primary ore control was lithology. Wallrock alteration is intense (carbonitization). The deposit is comprised of an irregular, broken lens of nearly massive and medium-grade, disseminated chromite with a maximum thickness of 12 feet. The country rock is a schistose, altered serpentine. It was said that there is some asbestos in sec. 2 (CDM Bulletin 195). Local rocks include Paleozoic marine rocks, undivided, unit 4 (Western Sierra Nevada).
Workings include surface and underground openings comprised of an open pit and inclined shaft.
Production information: 1,039 long tons of 30% chromic oxide. Idle since 1943.
The ore varied between 30 & 35% (Taliaferro (1918)). No estimates of reserves were made. Considerable lean ore remains at the bottonm of the caved workings. The average mineable grade of chromite is 32% and Fe is 7.2%. Analysis by CDMG in 1976 gave the following percentages of massive material: CR2O3: 26.31; FeO: 08.89; total Fe: 12.07; Al203: 29.52; and, MgO: ?; Cr:Fe = 1.92:1.
Select Mineral List Type
Standard Detailed Gallery Strunz Chemical ElementsDetailed Mineral List:
| ⓘ Formula: Fe2+Cr3+2O4 Description: Pemberton, H. Earl (1983) corrects the occurrence to magnesiochromite. References: |
| ⓘ Magnesiochromite Formula: MgCr2O4 |
Gallery:
List of minerals arranged by Strunz 10th Edition classification
| Group 4 - Oxides and Hydroxides | |||
|---|---|---|---|
| ⓘ | Chromite ? | 4.BB.05 | Fe2+Cr3+2O4 |
| ⓘ | Magnesiochromite | 4.BB.05 | MgCr2O4 |
List of minerals for each chemical element
| O | Oxygen | |
|---|---|---|
| O | ⓘ Chromite | Fe2+Cr23+O4 |
| O | ⓘ Magnesiochromite | MgCr2O4 |
| Mg | Magnesium | |
| Mg | ⓘ Magnesiochromite | MgCr2O4 |
| Cr | Chromium | |
| Cr | ⓘ Chromite | Fe2+Cr23+O4 |
| Cr | ⓘ Magnesiochromite | MgCr2O4 |
| Fe | Iron | |
| Fe | ⓘ Chromite | Fe2+Cr23+O4 |
Other Databases
| Link to USGS MRDS: | 10109168 |
|---|
Other Regions, Features and Areas containing this locality
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References
