| Deposit ID | 10310350 |
|---|---|
| MRDS ID | M035782 |
| Record type | Site |
| Current site name | Borealis Mine |
| Alternate or previous names | Deep Ore Flats, East Ridge, Freedom Flats, Gold View, Graben, Jaimes Ridge, Northeast Ridge orebodies |
| Related records | 10037638 |
| Geographic coordinates: | -118.75957, 38.38325 (WGS84) |
|---|---|
| Elevation | 2210 |
| Relative position | The Borealis gold property, located in Mineral County, Nevada is made up of 415 unpatented mining claims covering 13 square miles located about 15 miles southwest of Hawthorne, Nevada. |
Political divisions (FIPS codes)
Mineral(county)
Nevada(state)
United States(country)
North America(continent)
Land(continent)
USGS map quadrangles
Corey Peak(quadrangle 1:24,000 scale)
Excelsior Mountains(quadrangle 1:100,000 scale)
Walker Lake(quadrangle 1:250,000 scale)
Hydrologic units (watersheds)
East Walker(hydrologic unit)
Walker(hydrologic accounting unit)
Central Lahontan(hydrologic subregion)
Great Basin(hydrologic region)
Federal lands
Humboldt-Toiyabe National Forest(National Forest)
National Forest FS(Type of land area)
FS(Federal land areas administered by FS)
| Country | State | County |
|---|---|---|
| United States | Nevada | Mineral |
| Meridian | Township | Range | Section | Fraction | State |
|---|---|---|---|---|---|
| Mount Diablo | 006N | 029E | 16 17 | Nevada |
| Commodity | Importance |
|---|---|
| Gold | Primary |
| Silver | Secondary |
| Zinc Critical | Tertiary |
| Copper | Tertiary |
| Nickel Critical | Tertiary |
| Materials | Type of material |
|---|---|
| Gold | Ore |
| Cinnabar | Ore |
| Chalcopyrite | Ore |
| Chalcocite | Ore |
| Sphalerite | Ore |
| Covellite | Ore |
| Tetrahedrite | Ore |
| Tennantite | Ore |
| Enargite | Ore |
| Matildite | Ore |
| Nagyagite | Ore |
| Niccolite | Ore |
| Alunite | Ore |
| Feldspar | Ore |
| Barite | Ore |
| Pyrite | Ore |
| Hematite | Ore |
| Montmorillonite | Ore |
| Kaolinite | Ore |
| Marcasite | Ore |
| Arsenopyrite | Ore |
| Pyrrhotite | Ore |
| Quartz | Gangue |
| Model code | 104 |
|---|---|
| USGS model code | 25a |
| Deposit model name | Hot-spring Au-Ag |
| Mark3 model number | 45 |
| Host or associated | Host | ||||||||
|---|---|---|---|---|---|---|---|---|---|
| Rock type | Volcanic Rock (Aphanitic) > Intermediate Volcanic Rock > Andesite | ||||||||
| Rock type qualifier | flows | ||||||||
| |||||||||
| Host or associated | Host | ||||||||
|---|---|---|---|---|---|---|---|---|---|
| Rock type | Volcanic Rock (Aphanitic) > Pyroclastic Rock > Tuff | ||||||||
| Rock type qualifier | andesite | ||||||||
| |||||||||
| Host or associated | Host | ||||||||
|---|---|---|---|---|---|---|---|---|---|
| Rock type | Volcanic Rock (Aphanitic) > Pyroclastic Rock > Volcanic Breccia (Agglomerate) | ||||||||
| Rock type qualifier | andesite tuff breccia | ||||||||
| |||||||||
| (1) | -118.75957, 38.38325 |
|---|
| Type of structure | Regional |
|---|---|
| Structure description | Major regional structural trends affecting the mine area are the Walker Lane shear zone and the Borealis Trend. |
| Type of structure | Local |
| Structure description | NE-trending faults with subordinate N-S and E-W- striking structures. |
| General form | tabular to irregular |
|---|
| Operation type | Surface-Underground |
|---|---|
| Development status | Producer |
| Commodity type | Metallic |
| Deposit size | Medium |
| Significant | Yes |
| Discovery year | 1930 |
| Discoverer | S. W. Ivosevic of H.O.M.Co. |
| Year of first production | 1981 |
| Year of last production | 1990 |
| Production years | 1981-1990 |
| District name | Borealis District |
|---|---|
| District name | Lucky Boy District |
| Ownership category | National Forest |
|---|---|
| Area name | Carson City USFS administrative area |
| Type | Owner-Operator |
|---|---|
| Owner | Gryphon Gold |
| Year | 2006 |
Reid, R. F., Jr., 1984, The geology of the Borealis deposit: GSA Abstracts with Programs, 97th Ann. Mtg, Reno, NV.
NBMG Mining District File 200, Items 8, 9, Press Clippings.
Tooker, E.W., 19?, In USGS Bull 1646.
Strachan, D.G., 19?, Geologic Discussion of the Borealis Gold Deposit, Mineral Co., Nevada, in USGS Bull 1646.
Bulk-Mineable Precious Metals Symposium, 1987, Field Trip Guidebook.
NBMG, 1994, MI-1993
Golden Phoenix Co. website, 2006.
Gryphon Gold website, 2006.
Struhsacker, Eric, guidebook editor, 1994, Geological Society of Nevada Special Publication #20, Gold Deposits of the Central Walker Lane, Nevada: mineralization Style and Mine Closure Planning.
Eng, T., 1991, Geology and Mineralization of the Freedom Flats Gold Deposit, Borealis Mine, Mineral County, in Raines and others, Geology and Ore Deposits of the Great Basin, Symposium Proceedings, Reno, NV: Geological Society of Nevada, v. 2, p. 995-1019.
| Subject category | Comment text |
|---|---|
| Deposit | The original Borealis orebody was localized on the south side of a sporadically mineralized NE-trending fault zone. The pyroclastic breccia host rock is pervasively silicified by hydrothermal quartz and potassium feldspar with alunite and barite. Gold mineralization terminates abruptly along the gently NW-dipping contact with underlying andesitic flow rocks. A strongly acid-leached zone high in silver values is developed below this contact. The intensely brecciated acid-leached zone contains pods, stringers and stockwork veinlets of oxidized quartz-sulfide in a powdery bleached, siliceous matrix. Intense acid leaching (characterized by quartz, TiO2, clinochlore, barite, jarosite/alunite) grades outward to moderate argillic alteration (kaolin, montmorillonite). NE-trending small mineralized pods associated with intense acid leaching occur as structurally controlled replacements underneath and to the south of the main ore body. The deposit may be characterized as a hot spring vent ore. The current Borealis deposit is an epithermal gold system marked by large areas of silicification, hydrothermal brecciation, and argillic alteration. The gold deposits are structurally controlled along a series of northeasterly-trending faults that dip steeply to the northwest. The Borealis Zone has three separate targets: the Borealis Mine proper, Freedom Flats mine, and the Graben deposit. Gold occurs as micron-sized particles in highly altered andesite and tuff. The average gold-to-silver ratio is one to five. The Borealis district contains multiple coalescing hydrothermal centers having alteration and mineralization characteristic of high-sulfidation systems. Gold deposits of the district typically have high-grade gold mineralization centrally located along steeply dipping structures and have lower-grade gold mineralization both surrounding the high-grade and commonly occurring in more permeable volcanic rocks in relatively flat-lying zones. The gold deposits with minor amounts of silver mineralization are hosted by Miocene andesitic flows, laharic breccias and volcaniclastic tuffs, which generally strike northeasterly and dip shallowly to the northwest. Pediment gravels cover the altered-mineralized volcanic rocks at lower elevations along the mountain front and there is potential for discovery of more blind deposits, similar to the Graben and the Freedom Flats deposits. Parts of the greater Borealis project area with known occurrences of gold mineralization defined by historical exploration drilling and mine production include: Borealis, East Ridge and Gold View, Northeast Ridge, Freedom Flats, Deep Ore Flats (also known as Polaris), Cerro Duro, and Jaimes Ridge. All of these deposits still have gold mineralization remaining in place, contiguous with the portions of each individual deposit that previously has been mined. Alteration consists mainly of silicification, oxidation, argillization, and propylitization. The conduit for hydrothermal fluids was a 100-200 ft. wide core zone of silica breccia with abundant iron oxide minerals. The silica breccia zone narrows downward and grades downward into oxidized quartz-sulfide and unoxidized quartz-pyrite alteration. Argillic and propylitic alteration zones develop outward from core. Barren opal and chalcedonic silica overlie deposit. |
| Type | Date | Name | Affiliation | Comment |
|---|---|---|---|---|
| Reporter | 01-AUG-2006 | LaPointe, D.D. | Nevada Bureau of Mines and Geology | |
| Editor | 01-SEP-2007 | Schruben, Paul G. | U.S. Geological Survey | Converted from S&A FileMaker format to Oracle. Edit checks on rocks, units, and ages with Geolex search, and other fields. |
Supplemental information added by qvyshift.com. Not part of the original USGS MRDS record.
| Status | Active since 10/01/2013 |
|---|---|
| MSHA mine ID | 2601655 |
| Mine name (MSHA) | Borealis Mine |
| Current operator | Borealis Mining Company, LLC |
| Current controller (parent) | Andreas Steckenborn; Kelly Malcolm |
| Mine type | Surface (Metal / non-metal) |
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