Greater Goldstrike, North Mines

Site Name

Primary: Greater Goldstrike, North Mines
Secondary: Betze
Secondary: Bazza
Secondary: West Bazza
Secondary: Bazza Point
Secondary: Screamer
Secondary: Shalosky
Secondary: Long Lac
Secondary: Winston
Secondary: Post
Secondary: Lower Post
Secondary: Deep Post
Secondary: Rodeo
Secondary: Goldbug
Secondary: Barrel
Secondary: East Griffin
Secondary: West Griffin
Secondary: Pancana
Secondary: Betze-Post pit

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Commodity

Primary: Gold
Secondary: Silver
Tertiary: Arsenic

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Location

State: Nevada
County: Eureka
District: Lynn District

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Land Status

Land ownership: Private
Note: the land ownership field only identifies whether the area the mine is in is generally on public lands like Forest Service or BLM land, or if it is in an area that is generally private property. It does not definitively identify property status, nor does it indicate claim status or whether an area is open to prospecting. Always respect private property.

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Holdings

Not available

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Workings

Not available

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Ownership

Owner Name: Barrick Gold Corporation
Info Year: 2004

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Production

Not available

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Deposit

Record Type: Site
Operation Category: Producer
Deposit Type: disseminated
Operation Type: Surface-Underground
Year First Production: 1977
Year Last Production: 2004
Discovery Year: 1962
Years of Production:
Organization:
Significant: Y
Deposit Size: L

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Physiography

Not available

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Mineral Deposit Model

Model Name: Sediment-hosted Au

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Orebody

Form: tabular to irregular disseminated

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Structure

Type: R
Description: Roberts Mountains thrust

Type: L
Description: High angle faults striking NW to NNW

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Alterations

Alteration Type: L
Alteration Text: Decarbonitization and silicification of sedimentary host rocks are the predominant form of alteration. In the Betze-Post deposit, Arehart and others reported a 117 Ma age for gold mineralization, based on multiple 40Ar/ 39Ar and K/Ar dates on sericite, with no evidence of significant hydrothermal activity younger than 110 Ma.

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Rocks

Role: Host
Age Type: Host Rock Unit
Age Young: Ordovician

Name: Chert
Role: Host
Age Type: Host Rock
Age Young: Devonian

Name: Sandstone
Role: Host
Age Type: Host Rock
Age Young: Devonian

Name: Siltstone
Role: Host
Age Type: Host Rock
Age Young: Devonian

Name: Porphyry
Role: Associated
Description: biotite monzonite
Age Type: Associated Rock
Age in Years: 39.000000+-
Age Young: Middle Eocene

Name: Mudstone
Role: Host
Description: calcareous
Age Type: Host Rock
Age Young: Devonian

Name: Carbonate
Role: Host
Description: breccia
Age Type: Host Rock
Age Young: Devonian

Name: Limestone
Role: Host
Age Type: Host Rock
Age Young: Devonian

Name: Porphyry
Role: Associated
Description: diorite to granodiorite and quartz monzonite-
Age Type: Associated Rock
Age in Years: 158.000000+-
Age Young: Late Jurassic

Name: Quartz Monzonite
Role: Associated
Age Type: Associated Rock
Age in Years: 158.000000+-
Age Young: Late Jurassic

Name: Granodiorite
Role: Associated
Age Type: Associated Rock
Age in Years: 158.000000+-
Age Young: Late Jurassic

Name: Diorite
Role: Associated
Age Type: Associated Rock
Age in Years: 158.000000+-
Age Young: Late Jurassic

Role: Host
Age Type: Host Rock Unit
Age Young: Devonian

Role: Host
Age Type: Host Rock Unit
Age Young: Early Devonian
Age Old: Wenlock

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Analytical Data

Not available

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Materials

Ore: Gypsum
Ore: Hematite
Ore: Goethite
Ore: Stibnite
Ore: Barite
Ore: Alunite
Ore: Illite
Ore: Sericite
Ore: Dickite
Ore: Kaolinite
Ore: Marcasite
Ore: Pyrite
Ore: Quartz
Ore: Realgar
Ore: Gold
Ore: Calcite
Ore: Jarosite
Gangue: Orpiment

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Comments

Comment (Location): There are several orebodies that comprise the Greater Goldstrike north mines covering an aggregate area of a couple of square miles.

Comment (Workings): The Goldstrike property consists of 6870 acres. Betze and Post pits merged into a single large pit withunderground workings extending from it. The curent dimensions of the pit (9/2004) are 9900 feet long by 7500 feet wide by 1500 feet deep. Strip ratio is 6.4:1. This pit plan includes the removal of 815.6 million tons waste. Water inflow into the potential pit at 2000 ft. below the general land surface is expected to be approximately 40,000 gallons/min at 125 degrees F. Sulfide ore is treated in a 5000 ton/day autoclave circuit commissioned 2/2/90. The CIL plant was to be converted progressively to give a total sulfide capacity of 12,750 ton/day by 1993.

Comment (Economic Factors): Since purchasing Goldstrike in 1986, Barrick has increased the property significantly, from 600,000 ounces reserves in 1986 to 19.1 million ounces reserves in 2003. Barrick?s Goldstrike property has produced 25.6 million ounces of gold through 2003, more than 2 million ounces per year from 1995 through 2003. In 2003, Barrick reported proven and probable reserves for the entire Goldstrike property as about 119 million tons of ore grading 0.161 ounces of gold per ton, for a total of more than 19 million ounces of gold. There is also an additional inferred mineral resource of more than 43 million tons of ore grading 0.110 ounces of gold per ton, for an additional 4.753 million ounces of gold. Approximate total gold endowment at Betze-Post as of 2002 was 40 million ounces (1,244 t) of gold. This figure did not include endowments of Rodeo, 4.0 million ounces (124 t), Post, 3.5 million ounces (109 t) of gold, and Meikle, 7.0 million ounces (218 t) of gold. In their 2005 Annual Report, Barrick Gold Corp. announced that reserves at the Goldstrike Open-Pit operations aggregate 114,512,000 tons grading 0.128 opt Au proven+probable, and Goldstrike underground operations aggregate 7,318,000 tons @grading 0.279 opt Au proven+probable.

Comment (Environment): These deposits are situated north of the Goldstrike Stock.

Comment (Identification): This record encompasses several deposits described individually by earlier records M242254, W700377, RE00290, W700378,W700371, as well as adjacent orebodies without earlier MRDS records.

Comment (Development): The first discovery of gold in the Goldstrike area was in 1962 by Harry Ranspot of Atlas Minerals. The only evidence of earlier mining activity in the Goldstrike area were small mercury workings, located along the Post fault zone, south of the Meikle deposit. Seventeen holes were drilled in 1963, many of which intersected sporadic gold mineralization up to 0.31 opt (10.6 g/t) of gold in siliciclastic rocks. One of these drill holes intersected the Bazza deposit and two others cut mineralization near the Number 9 and Winston deposits. Trenching and drilling by Newmont Mining in 1966 discovered low-grade gold in fault zones cutting a diorite intrusion (the Goldstrike stock). Although this early exploration identified significant gold grades,no development occurred due to the low gold price at the time. Between 1975-77, exploration funded by Lac Minerals Ltd. identified soil geochemical anomalies and low grade gold mineralization. A 2000 ton sample leached on a pad gave poor recoveries because of high clay content and compaction. Further batch mining was done from 1978 onward. The Post surface orebody was discovered by Western States Minerals in 1982 using diamond drilling. In October 1986, Western States drilled one deep core hole to 1800 ft., intersecting 391 ft./0.193 opt gold at a depth of 1164-1555 ft. American Barrick purchased the Goldstrike property in 1986 for $62 million from the joint venture of Pancana Industries and Western States Minerals Corporation. American Barrick continued the deep drilling and identified reserves of 9.3 million tons at 0.283 opt gold at Deep Post by 1989. In March 1987, a deep hole drilled to test an IP anomaly 3000 ft. NW of Post intersected the Betze orebody at a depth of approximately 1000 ft. Further drilling in 1987 indicated that ore was continuous between Deep Post and Betze. In January 1989, the Betze development plan went into effect, covering mining to the year 2000 and processing to 2006. The Betze pit was developed as a progressive expansion of the existing Post pit. In August 1989, Newmont Gold Co.reported a drill intersection of 350 ft. at 0.768 opt gold from a hole collared a few hundred feet south of the Newmont/Barrick property boundary. This intercept was from a portion of the Deep Post orebody that extends onto Newmont Gold's property. Negotiations were undertaken between Barrick and Newmont for the joint development of the Deep Post orebody. 1994 saw the discovery of mineralized zones at Screamer, North Post, West Betze, Rodeo, and Griffin, all within the greater Goldstrike Mine area. The Goldstrike property (consisting of the Meikle and Betze-Post Mines) was Barrick's largest producer again in 2002, completing its eighth straight year of production in excess of 2 million ounces. During 2002, 80% of production was replaced through reserve expansion. The property is expected to continue to produce at the 2-million-ounce level for at least the next 4 years. In late 2004, Barrick reported the underground exploration and Betze Drift at Goldstrike out of the Betze-Post open pit is going well and is expected to be completed by the end of March 2005. The new drift is providing an exploration platform and another exit for miners at the Rodeo and Meikle underground mines at Goldstrike, while surface exploration continues at Betze-Post.

Comment (Commodity): Ore Materials: Native gold

Comment (Commodity): Gangue Materials: orpiment, realgar, quartz, pyrite, marcasite, kaolinite, dickite, sericite, illite, alunite, barite, stibnite, goethite, hematite, jarosite, gypsum, calcite

Comment (Deposit): Betze-Post, the largest gold deposit in the district and in the Carlin trend, is subdivided into three subdeposits, which are from east to west, Deep Post, Betze, and Screamer. In addition, the previously mined Post deposit (or Post oxide) was located above the Deep Post deposit and is therefore part of the overall Betze-Post mineralized system. The higher grade ore is generally found adjacent to faults and in crests of folds, below impermeable units. The deposit contains both sulfide and oxide ore. The Lower Post and Betze orebodies are horizontally and vertically adjacent parts of the same orebody, discovered and then named separately. Betze is NW of and below Post; the Lower Post is directly below Post. Supergene alunite from Post was K/Ar dated at 8.48 to 9.58 Ma. The Post orebody is oxide ore, hosted by Vinini Formation. The Lower Post/Betze ores are refractory, hosted by Popovich and to a lesser extent Roberts Mountains Formation. The trend of secondary mineralization at Lower Post/Betze is N40-70E. Gold occurs as micron to submicron-sized particles associated with quartz and clays in the oxide zones and with pyrite and marcasite in the sulfide zones. Simple refractory ore in the lower portions of the Post orebody is characterized by silicification with 5-10% disseminated pyrite. Realgar and orpiment occur in the Deep Post orebody spatially associated with gold mineralization but contain significantly less gold than the fine-grained iron sulfides.

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References

Reference (Deposit): Barrick Gold Corp. 2002 Annual Report.

Reference (Deposit): Keith Bettles, 2002, Exploration and Geology, 1962 to 2002, at the Goldstrike Property, Carlin Trend, Nevada; in NBMG Bull. 111.

Reference (Deposit): Barrick 2005 Annual Report.

Reference (Deposit): "Striking It Rich for American Barrick", Canadian Mining Journal, November 1989, v. 110, no. 11, p. 45-62.

Reference (Deposit): Huspeni, J.R., 1990, Geology of the Post Gold Deposit [Abs]: Geology and Ore Deposits of the Great Basin, Reno/Sparks, Nevada, 1990, p. 67.

Reference (Deposit): Erdman, J.A., et al., 1990, Gallium, A Rediscovered Pathfinder Element; Example, Sagebrush over the Betze Gold Deposit, NV, Explore, no. 68, p. 5-6.

Reference (Deposit): Knutsen, G. C., Bettles, K. H., Sulfrian, C. E., and Zimmerman, C. J., 1987, Discovery and Geology of the Post Gold Deposit, Eureka County, Nevada: Society of Mining Engineers Preprint Number 87-86, 6 p.

Reference (Deposit): Newmont Gold Corporation 1990 Annual Report

Reference (Deposit): Nevada Division of Mine Inspection, Directory of Nevada Mine Operations Active During Calendar Year 1983, 1982, 1981.

Reference (Deposit): Bonham, H.F. 1986, NBMG Map 91.

Reference (Deposit): Bonham, H.F. 1988, in NBMG MI-1987.

Reference (Deposit): Mining Journal/Montagu Mining Finance Database 8/10/91

Reference (Deposit): "Goldstrike Mine", Mining Magazine, October 1989, v. 161, no. 4, p. 269-272.

Reference (Deposit): "American Barrick - Growing Fast with Goldstrike", International Mining, April 1989, v. 6, no. 4, p. 9-11.

Reference (Deposit): McCarthy, J.H., et al., 1988, Evaluation of Multiple Geochemical Sample Media at the Betze Gold Deposit, Eureka County, Nevada, in Schinder, K.S., ed, USGS Research on Mineral Resources - 1989, Program and Abstracts, USGS Circular 1035, p. 45-47.

Reference (Deposit): "A New Trend At Carlin", Mining Magazine, March 1988, P. 166.

Reference (Deposit): Rocky Mountain Pay Dirt, June 1988, P. 3a.

Reference (Deposit): NBMG, 1991, The Nevada Mineral Industry - 1990, NBMG Special Publication MI-1990.

Reference (Deposit): NBMG, 1994, MI-1993

Reference (Deposit): Nevada Division of Minerals, 1994

Reference (Deposit): American Barrick, 1993 Annual Report

Reference (Deposit): Long, K.R., DeYoung, J.H., Jr., and Ludington, S.D., 1998, Database of significant deposits of gold, silver, copper, lead, and zinc in the United States; Part A, Database description and analysis; part B, Digital database: U.S. Geological Survey Open-File Report 98-206, 33 p., one 3.5 inch diskette

Reference (Deposit): Christensen, O. D., Knutsen, G. C., and Ekburg, C. E., 1987, Disseminated Gold Deposits of the Carlin Trend, Eureka and Elko Counties, Nevada: Society of Mining Engineers Preprint Number 87-84, 7 p.

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Nevada Gold

Nevada has a total of 368 distinct gold districts. Of the of those, just 36 are major producers with production and/or reserves of over 1,000,000 ounces, 49 have production and/or reserves of over 100,000 ounces, with the rest having less than 100,000 ounces. Read more: Gold Districts of Nevada.