Irelan Mine (Ireland Mine), Minnesota Flat, Alleghany Mining District (Forest Mining District), Sierra County, California, USAi
| Regional Level Types | |
|---|---|
| Irelan Mine (Ireland Mine) | Mine |
| Minnesota Flat | Flat |
| Alleghany Mining District (Forest Mining District) | Mining District |
| Sierra County | County |
| California | State |
| USA | Country |
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Latitude & Longitude (WGS84):
39° 26' 25'' North , 120° 49' 24'' West
Latitude & Longitude (decimal):
Type:
Köppen climate type:
Nearest Settlements:
| Place | Population | Distance |
|---|---|---|
| Washington | 185 (2011) | 9.2km |
| Downieville | 282 (2011) | 13.2km |
| Pike | 134 (2011) | 15.0km |
| Camptonville | 158 (2011) | 19.4km |
| Sierra City | 221 (2011) | 21.4km |
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 | 32km |
A former lode Au mine located in sec. 11, T18N, R10E, MDM, 1.2 km (0.8 mile) SSE of Minnesota Flat and about 1¾ miles SSE of Allegahny, on National Forest land. MRDS database stated accuracy for this location is 100 meters.
Mineralization is a vein deposit hosted in gabbro, schist, tuff, and slate. The ore body strikes N60W and dips 50NE at a thickness of 1.52 meters. There are 2 veins in tuffs with slates intruded by schistose gabbro with intense shearing and alteration close to the vein. Tuffs and slate are hanging wall of the E vein and the footwall of the W vein, suggesting reverse movement on both veins. Two other smaller veins occur in the upper workings. The vein changes strike sharply from N60W to N30W for 500 to 1,000 feet, then reverse to its original direction. The dip varies from 30 to 70NE, being flatter at surface. Quartz is lacking in places. Post-mineralization movement, with little gouge, but some quartz cemented quartz breccia, indicates movement prior to vein filling. There is also a small post-mineralization transverse fault. Arsenopyrite was crushed before the Au was introduced. The best ore is near the surface. High-grade pockets were said to be where the quartz is thickest. There is a possible correlation of high-grade bunches with stringers branching from the wall on the hanging wall side. Local alteration includes carbonitization. Local rocks include Mesozoic gabbroic rocks, unit 2 (undivided).
Workings include surface and underground openings with an overall depth of 97.54 meters and an overall length of 304.8 meters and comprised of adits 1,500 feet apart, winzes, and drifts with shallow surface workings.
Production data are found in: Ferguson & Gannett (1932).
Select Mineral List Type
Standard Detailed Gallery Strunz Chemical ElementsDetailed Mineral List:
| ⓘ Arsenopyrite Formula: FeAsS |
| ⓘ Muscovite Formula: KAl2(AlSi3O10)(OH)2 |
| ⓘ Muscovite var. Mariposite Formula: K(Al,Cr)2(Al,Si)4O10(OH)2 |
| ⓘ Muscovite var. Phengite Formula: KAl1.5(Mg,Fe)0.5(Al0.5Si3.5O10)(OH)2 |
| ⓘ 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 2 - Sulphides and Sulfosalts | |||
| ⓘ | Arsenopyrite | 2.EB.20 | FeAsS |
| Group 4 - Oxides and Hydroxides | |||
| ⓘ | Quartz | 4.DA.05 | SiO2 |
| Group 9 - Silicates | |||
| ⓘ | Muscovite | 9.EC.15 | KAl2(AlSi3O10)(OH)2 |
| ⓘ | var. Phengite | 9.EC.15 | KAl1.5(Mg,Fe)0.5(Al0.5Si3.5O10)(OH)2 |
| ⓘ | var. Mariposite | 9.EC.15 | K(Al,Cr)2(Al,Si)4O10(OH)2 |
List of minerals for each chemical element
| H | Hydrogen | |
|---|---|---|
| H | ⓘ Muscovite | KAl2(AlSi3O10)(OH)2 |
| H | ⓘ Muscovite var. Phengite | KAl1.5(Mg,Fe)0.5(Al0.5Si3.5O10)(OH)2 |
| H | ⓘ Muscovite var. Mariposite | K(Al,Cr)2(Al,Si)4O10(OH)2 |
| O | Oxygen | |
| O | ⓘ Muscovite | KAl2(AlSi3O10)(OH)2 |
| O | ⓘ Muscovite var. Phengite | KAl1.5(Mg,Fe)0.5(Al0.5Si3.5O10)(OH)2 |
| O | ⓘ Quartz | SiO2 |
| O | ⓘ Muscovite var. Mariposite | K(Al,Cr)2(Al,Si)4O10(OH)2 |
| Mg | Magnesium | |
| Mg | ⓘ Muscovite var. Phengite | KAl1.5(Mg,Fe)0.5(Al0.5Si3.5O10)(OH)2 |
| Al | Aluminium | |
| Al | ⓘ Muscovite | KAl2(AlSi3O10)(OH)2 |
| Al | ⓘ Muscovite var. Phengite | KAl1.5(Mg,Fe)0.5(Al0.5Si3.5O10)(OH)2 |
| Al | ⓘ Muscovite var. Mariposite | K(Al,Cr)2(Al,Si)4O10(OH)2 |
| Si | Silicon | |
| Si | ⓘ Muscovite | KAl2(AlSi3O10)(OH)2 |
| Si | ⓘ Muscovite var. Phengite | KAl1.5(Mg,Fe)0.5(Al0.5Si3.5O10)(OH)2 |
| Si | ⓘ Quartz | SiO2 |
| Si | ⓘ Muscovite var. Mariposite | K(Al,Cr)2(Al,Si)4O10(OH)2 |
| S | Sulfur | |
| S | ⓘ Arsenopyrite | FeAsS |
| K | Potassium | |
| K | ⓘ Muscovite | KAl2(AlSi3O10)(OH)2 |
| K | ⓘ Muscovite var. Phengite | KAl1.5(Mg,Fe)0.5(Al0.5Si3.5O10)(OH)2 |
| K | ⓘ Muscovite var. Mariposite | K(Al,Cr)2(Al,Si)4O10(OH)2 |
| Cr | Chromium | |
| Cr | ⓘ Muscovite var. Mariposite | K(Al,Cr)2(Al,Si)4O10(OH)2 |
| Fe | Iron | |
| Fe | ⓘ Arsenopyrite | FeAsS |
| Fe | ⓘ Muscovite var. Phengite | KAl1.5(Mg,Fe)0.5(Al0.5Si3.5O10)(OH)2 |
| As | Arsenic | |
| As | ⓘ Arsenopyrite | FeAsS |
| Au | Gold | |
| Au | ⓘ Native Gold | Au |
Other Databases
| Link to USGS MRDS: | 10106529 |
|---|
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 #0060910166
