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Gemfield Gold Deposit

Producer in Esmeralda county in Nevada, United States with commodities Gold, Silver, Copper
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Sections on this page
  1. Identification information
  2. Geographic coordinates
  3. Site location context
  4. Geographic areas
  5. Public Land Survey System information
  6. Commodities
  7. Materials information
  8. Alteration
  9. Mineral occurrence model information
  10. Host and associated rocks
  11. Nearby scientific data
  12. Geologic structures
  13. Ore body information
  14. Controls for ore emplacement
  15. Economic information about the deposit and operations
  16. Mining district
  17. Land status
  18. Ownership information
  19. Bibliographic references
  20. General comments
  21. Reporter information

Geologic information

Identification information

Deposit ID 10310419
MRDS ID W002900
Record type Site
Current site name Gemfield Gold Deposit
Related records 10310328, 10310417, 10310418, 60001656

Comments on the site identification

  • This new record is for the current Gemfield deposit of Metallic Ventures, which is one of three Metallic Ventures properties in the historic Goldfield District: Goldfield Main, McMahon Ridge, and Gemfield, each of which has its own record since they are separate and discrete deposits located a few miles apart. The older MRDS record W002900 describes the historic Goldfield District.

Geographic coordinates

Geographic coordinates: -117.23341, 37.71023 (WGS84)
Elevation 1830
Relative position The deposit is located about two miles north of the historic mining town of Goldfield about 28 miles south of Tonopah, near the east border of Esmeralda County

Site location context

Political divisions (FIPS codes)

Esmeralda(county)

Nevada(state)

United States(country)

North America(continent)

Land(continent)

USGS map quadrangles

Goldfield(quadrangle 1:24,000 scale)

Goldfield(quadrangle 1:100,000 scale)

Goldfield(quadrangle 1:250,000 scale)

Hydrologic units (watersheds)

Ralston-Stone Cabin Valleys(hydrologic unit)

Central Nevada Desert Basins(hydrologic accounting unit)

Central Nevada Desert Basins(hydrologic subregion)

Great Basin(hydrologic region)

Geographic areas

Country State County
United States Nevada Esmeralda

Public Land Survey System information

Meridian Township Range Section Fraction State
Mount Diablo 002S 042E 27 Nevada

Comments on the location information

  • The Gemfield Area is located about two miles north of the town of Goldfield, straddling U.S. Highway 95.

Commodities

Commodity Importance
Gold Primary
Silver Secondary
Copper Secondary

Comments on the commodity information

  • Ore Materials: gold
  • Gangue Materials: quartz, alunite, barite, gypsum, limonite, kaolin

Materials information

Materials Type of material
Gold Ore
Quartz Gangue
Alunite Gangue
Barite Gangue
Gypsum Gangue
Limonite Gangue
Kaolin Gangue

Alteration

  • (Local) Large envelopes of intense argillic alteration surround most of the ore zones with silicification of core ore zones.

Mineral occurrence model information

Model code 154
USGS model code 25e
Deposit model name Epithermal quartz-alunite Au
Mark3 model number 38

Host and associated rocks

  • Host or associated Host
    Rock type Volcanic Rock (Aphanitic) > Felsic Volcanic Rock > Rhyolite
    Rock unit name Sandstorm Rhyolite
    Stratigraphic age (youngest) Oligocene

Nearby scientific data

(1) -117.23341, 37.71023
ListMap

Economic information

Geologic structures

Type of structure Local
Structure description The Gemfield Deposit is located to the west of the ring fracture zone that controls the main Goldfield deposits.
Type of structure Regional
Structure description Tertiary deposits are domed and faulted by steeply dipping post Miocene: N-S and E-W faults.

Ore body information

  • General form Irregular to tabular or knobby

Controls for ore emplacement

  • The ore-bearing structures are generally north-south trending and sub-parallel to the strike of the ring-fracture zone.

Comments on the geologic information

  • The Goldfield mining district is located at the site of a complex and long-lived igneous intrusive and volcanic center that is defined by eruptive vents and curviplanar faults. The local volcanic stratigraphy, a moderately well-defined ring-fracture zone, concentric structural doming, high sulfidation-style quartz-alunite hydrothermal alteration, and widespread copper-gold mineralization are all genetically related to the emplacement of a large dominantly andesitic igneous complex and the most significant components of which are late Oligocene to early Miocene in age..

Economic information about the deposit and operations

Operation type Surface-Underground
Development status Producer
Commodity type Metallic
Deposit size Medium
Significant Yes
Discovery year 1902
Year of first production 1904
Year of last production 1970
Production years 1904-1970s

Mining district

District name Goldfield District:

Land status

Ownership category Private
Ownership category BLM Administrative Area
Area name Tonopah District BLM

Ownership information

  • Type Owner-Operator
    Owner Metallic Ventures Inc.
    Year 2004

Comments on the workings information

  • Older workings were predominantly underground with later surface workings.

Comments on other economic factors

  • Historic recorded production from the main Goldfield district is 4,190,133 ounces of gold at an average 0.541 oz/ton gold, including about 160,800 ounces of gold from reworked tailings.
    1996 reserves of the Gemfield area were reported at 9.5 million tons of ore grading 0.04 opt Au.for a total of about 500,000 ounces of gold.
    In 2006, Metallic Ventures Gold Inc. announced recent in-fill drill results and reported a resource for the Gemfield Project of 9,500,000 tons of material grading 0.040 ounces of gold per ton.

Comments on development

  • Metallic Ventures Inc. acquired the Gemfield property from Newmont Capital Limited on August 29, 2002, initiated a 28-hole, 10,660-foot drilling program in November 2002, and completed the program in December 2002. The drill program confirmed the continuity of the existing 500,000-ounce gold resource at Gemfield and enhanced the overall grade. An additional 50,000-foot drilling program in 2004 increased the ounces and grade of the resource and Metallic Ventures was planning to implement a feasibility study of the Gemfield and McMahon Ridge deposits by the third quarter of 2004.

    In mid-2006, Metallic Ventures Gold Inc. announced that recent in-fill drill results at the Gemfield Project include 117.5-212.5 feet @ 0.026 opt Au (GEM-400); 82.5-205 feet @ 0.024 opt Au (GEM-401); 60- 235 feet @ 0.020 opt Au (GEM-402); 90-190 feet @ 0.025 opt Au (GEM-403); 105-185 feet @ 0.918 opt Au (GEM-404) and 52.5- 225 feet @ 0.030 opt Au (GEM-405).

Reference information

Bibliographic references

General comments

Subject category Comment text
Deposit The drill-defined parts of the Gemfield mineralized area has the following dimensions: 2,500 ft long, 2,000 ft down dip, and an average 150 ft thick.
Almost all of the precious and base metal production recorded from the Goldfield mining district has come from rich epithermal bonanza ore bodies in the area northeast of the Goldfield town site. These ore bodies occur within silicified hydrothermal alteration zones. Mineralization in the argillized wall rock envelopes appears to be leakage zones emanating from core silicified zones. Ore zones are commonly associated with silicification and/or free quartz surrounded by large envelopes of intense argillic alteration.
In the main district, gold-copper ores were found in a series of pipe-like shoots referred to locally as ledges, the most productive of which occurred where the east-west striking Goldfield structural trend intersects a mile-long arcuate section of inferred intrusive-related ring-fracture zone. Although the major ore bodies are hosted in a complex intersecting set of faults and fracture zones, the ore-bearing structures are generally north-south trending and sub-parallel to the strike of the ring-fracture zone in that location.

Reporter information

Type Date Name Affiliation Comment
Reporter 01-MAY-2004 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.

Beyond USGS

Supplemental information added by qvyshift.com. Not part of the original USGS MRDS record.

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