Sierra Iron Mine (Sierra Mine; Sierra Iron Co.; Lake Hawley and Spencer Lake deposit), Hawley Lake, Sierra City Mining District, Sierra County, California, USAi
This page is currently not sponsored. Click here to sponsor this page.
Latitude & Longitude (WGS84):
39° 41' 52'' North , 120° 42' 51'' West
Latitude & Longitude (decimal):
Type:
Köppen climate type:
Nearest Settlements:
| Place | Population | Distance |
|---|---|---|
| Plumas Eureka (historical) | 339 (2011) | 6.8km |
| Graeagle | 737 (2011) | 11.2km |
| Plumas Eureka | 339 (2017) | 11.6km |
| Valley Ranch | 109 (2011) | 13.4km |
| C-Road | 150 (2011) | 13.7km |
A former Fe occurrence/prospect/mine located in secs. 11, 14 & 23, T21N, R11E, MDM, 1.6 km (1.0 mile) N of Hawley Lake, 1.1 km (3,500 feet) E of Spencer Lakes (about 2,000 feet E of the eastern lake) and about 5 miles S of Johnsville (Plumas County), on private land within a National Forest area. MRDS database stated accuracy for this location is 100 meters.
Mineralization is a contact metasomatic deposit hosted in metamorphic rock. The ore body is irregular to lenticular in form. The metamorphic rocks in the area belong to the Calaveras Formation. Most of the Calaveras Formation in the vicinity of the iron ore deposits are of low-grade metamorphic rocks derived from fine, sandy sediments, from tuff and tuff breccias (rhyolite to dacite), from mixtures of calcareous and clastic sediments and from cherts. A few thin beds of metamorphosed conglomerate and of metamorphosed volcanic breccia are present. Local alteration includes dynamothermal metamorphism. Associated rocks include Pennsylvanian quartz monzonite. Local rocks include Paleozoic marine rocks, undivided, unit 4 (Western Sierra Nevada).
There are two groups of deposits about 1¼ miles apart, one consisting of 13 small deposits near Lake Spencer and a larger one, 1 mile SE of Lake Hawley. A more detailed description of each deposit is found in the report by Durrell and Proctor. The magnetite deposits are of 2 types, depending upon the rock in which they were formed. The Lake Hawley group and most of the Spencer Lake group consists essentially of talc and magnetite. The second type consists of magnetite and calcite. The 2 groups contain both types in combination.
Local geologic structures include folds and faults.
Average figures obtained through calculations on 7 samples from Lake Hawley and 1 sample from Spencer Lake suggest the grade of ore to be about 21% Fe.
Resource data are found in: Durrell and Proctor (1948).
Reserves and resources: Type: in-situ; estimate year: 1948; total resources: 36,000 metric tons of ore @ 21 weight percent Fe.
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
4 valid minerals.
Detailed Mineral List:
| ⓘ 'Apatite' Formula: Ca5(PO4)3(Cl/F/OH) Habit: Prismatic Colour: White Description: Occurs as crystals to ¾ inches long in cavities in magnetite ore. |
| ⓘ Calcite Formula: CaCO3 |
| ⓘ 'Chlorite Group' Description: Occurs as crystals. |
| ⓘ Dolomite Formula: CaMg(CO3)2 |
| ⓘ Magnetite Formula: Fe2+Fe3+2O4 References: |
| ⓘ Talc Formula: Mg3Si4O10(OH)2 |
Gallery:
List of minerals arranged by Strunz 10th Edition classification
| Group 4 - Oxides and Hydroxides | |||
|---|---|---|---|
| ⓘ | Magnetite | 4.BB.05 | Fe2+Fe3+2O4 |
| Group 5 - Nitrates and Carbonates | |||
| ⓘ | Calcite | 5.AB.05 | CaCO3 |
| ⓘ | Dolomite | 5.AB.10 | CaMg(CO3)2 |
| Group 9 - Silicates | |||
| ⓘ | Talc | 9.EC.05 | Mg3Si4O10(OH)2 |
| Unclassified | |||
| ⓘ | 'Chlorite Group' | - | |
| ⓘ | 'Apatite' | - | Ca5(PO4)3(Cl/F/OH) |
List of minerals for each chemical element
| H | Hydrogen | |
|---|---|---|
| H | ⓘ Talc | Mg3Si4O10(OH)2 |
| H | ⓘ Apatite | Ca5(PO4)3(Cl/F/OH) |
| C | Carbon | |
| C | ⓘ Calcite | CaCO3 |
| C | ⓘ Dolomite | CaMg(CO3)2 |
| O | Oxygen | |
| O | ⓘ Calcite | CaCO3 |
| O | ⓘ Dolomite | CaMg(CO3)2 |
| O | ⓘ Magnetite | Fe2+Fe23+O4 |
| O | ⓘ Talc | Mg3Si4O10(OH)2 |
| O | ⓘ Apatite | Ca5(PO4)3(Cl/F/OH) |
| F | Fluorine | |
| F | ⓘ Apatite | Ca5(PO4)3(Cl/F/OH) |
| Mg | Magnesium | |
| Mg | ⓘ Dolomite | CaMg(CO3)2 |
| Mg | ⓘ Talc | Mg3Si4O10(OH)2 |
| Si | Silicon | |
| Si | ⓘ Talc | Mg3Si4O10(OH)2 |
| P | Phosphorus | |
| P | ⓘ Apatite | Ca5(PO4)3(Cl/F/OH) |
| Cl | Chlorine | |
| Cl | ⓘ Apatite | Ca5(PO4)3(Cl/F/OH) |
| Ca | Calcium | |
| Ca | ⓘ Calcite | CaCO3 |
| Ca | ⓘ Dolomite | CaMg(CO3)2 |
| Ca | ⓘ Apatite | Ca5(PO4)3(Cl/F/OH) |
| Fe | Iron | |
| Fe | ⓘ Magnetite | Fe2+Fe23+O4 |
Other Databases
| Link to USGS MRDS: | 10098348 |
|---|
Other Regions, Features and Areas containing this locality
North AmericaContinent
North America PlateTectonic Plate
- Shoofly-Olds Ferry DomainDomain
- Sierra Nevada BatholithVolcanic Arc
USA
- Sierra NevadaMountain Range
This page contains all mineral locality references listed on mindat.org. This does not claim to be a complete list. If you know of more minerals from this site, please register so you can add to our database. This locality information is for reference purposes only. You should never attempt to
visit any sites listed in mindat.org without first ensuring that you have the permission of the land and/or mineral rights holders
for access and that you are aware of all safety precautions necessary.
References
(n.d.) Minerals Availability System (MAS), U.S. Bureau of Mines.file #0060910465
