Deep Post Mine

Site Name

Primary: Deep Post Mine

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Commodity

Primary: Gold
Secondary: Silver
Secondary: Arsenic

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Location

State: Nevada
County: Eureka
District: Carlin Trend

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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 in cooperation with Newmont Gold
Info Year: 2006

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Production

Not available

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Deposit

Record Type: Site
Operation Category: Producer
Deposit Type: epithermal, sediment-hosted, disseminated gold
Operation Type: Surface
Year First Production: 1986
Discovery Year: 1982
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: STRATIFORM (APPROXIMATELY)

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Structure

Type: R
Description: ROBERTS MOUNTAIN THRUST

Type: L
Description: N-NNW-TRENDING ZONE CONSIDERED MAIN HYDROTHERMAL CONDUIT; NNW TO N, AND NE-STRIKING FAULTS

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Alterations

Alteration Type: L
Alteration Text: Decarbonization; argillic and silicic hydrothermal; oxidation.

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Rocks

Name: Chert
Role: Host
Age Type: Host Rock
Age Young: Early Devonian
Age Old: Wenlock

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

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

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

Name: Argillite
Role: Host
Age Type: Host Rock
Age Young: Ordovician

Name: Diorite
Role: Associated
Age Type: Associated Rock
Age Young: Jurassic

Name: Latite
Role: Associated
Age Type: Associated Rock
Age in Years: 39.000000+-
Age Young: Middle Eocene

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

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

Name: Limestone
Role: Host
Age Type: Host Rock
Age Young: Early Devonian
Age Old: Wenlock

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Analytical Data

Not available

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Materials

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

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Comments

Comment (Commodity): Commodity Info: Au 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 lower Post/Betze orebody is characterized by silicification with kaolinite & 5-10% disseminated pyrite. Carbon found distal and probably unrelated to the orebodies. Increasing Au grades associated with increasing amounts of pyrite/marcasite.

Comment (Commodity): Ore Materials: GOLD, AURIFEROUS PYRITE, ARSENIAN PYRITE, ARSENOPYRITE, MARCASITE

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

Comment (Geology): AREHART, FOLAND, ET AL. (1993, LATEST PUB. ON THIS DEPOSIT) GIVES AGE OF MINERALIZATION AS 117 MA. OTHER POSSIBLE AGES OF MINERALIZATION ARE: 36-37 MA, 39 MA, OR 158 MA. THE LOWER POST, BETZE, AND DEEP POST DEPOSITS LIE BENEATH THE POST DEPOSIT AND SPACIALLY DISTINCT FROM POST. POST LIES ON THE UPPER PLATE OF THE ROBERTS MOUNTAIN THRUST; BETZE & LOWER POST ARE IN THE LOWER PLATE OF THIS THRUST. LOWER POST AND BETZE ARE A SINGLE OREBODY (AREHART ET AL). ASSOCIATED IGNEOUS ROCKS, SHOWN ABOVE, ALSO HOST ORE IN THE POST DEPOSIT. NNW TO N FAULTS AND SOME NE FAULTS SHOW MOVEMENT AFTER ORE FORMATION. FAULTING CAUSED BRECCIATION AND PREPARATION FOR HIGHER GRADE MINERALIZATION. COLLAPSE & HYDROTHERMAL BRECCIAS OF ABOVE-NAMED HOST ROCKS ALSO HOST ORE. MINOR AU MINERALIZATION FOUND IN GOLDSTRIKE INTRUSIVE, USUALLY ALONG FAULTS OR JOINTS. AMERICAN BARRICK AND NEWMONT USE DIFFERENT NAMES FOR THE SAME UNITS (SUCH AS ROBERTS MOUNTAIN FM.).

Comment (Identification): This record includes information from MRDS record W700371 for the Post Deposit

Comment (Workings): OPEN PIT

Comment (Economic Factors): The pre-mine resource for the Deep Post deposit was listed in 2002 as 4 million ounces of gold.

Comment (Deposit): 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. Lower Post and Betze 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 has been K/Ar dated at 8.48 to 9.58 Ma (Arehart, cited in Lauha & Bettles). The Post orebody is oxide ore, hosted by Vinini Fm. The Lower Post/Betze ores are refractory, hosted by Popovich and to a lesser extent Roberts Mountains Formation. The secondary mineralization trend at Lower Post/Betze is N40-70E.

Comment (Development): Anomalous gold detected in outcrops; orebody encountered in first drill hole. Western States Minerals commenced mining in 1986, and sold the Post deposit to Barrick Goldstrike in January 1987. Lower Post was discovered by deep drilling in 1987. Further drilling in 1987 defined the Betze orebody, "the largest deposit discovered to date in the Carlin trend" (Lauha & Bettles, 1993). The Post orebody is mined by Barrick Goldstrike as a major ore source for the Goldstrike mine processing facilities. Most reserves are mined from Betze pit, which was expected to reach depth of approx. 1,600 feet, with a stripping ratio of 1:7. Refractory ore is processed by autoclave , which is expected to reach a daily capacity of 15,000 tons/day in 1993. The Newmont portion of Lower Post will be mined sometime after 1993. ; econ.com: cyanidation relatively unsuccessful on refratory sufide ore, so barrick processes such ores by roasting or pressure oxidation, then cyanidation.

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References

Reference (Deposit): Rocky Mountain Pay Dirt, March, 1988, p. 4a-5a.

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

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): Albino, George, 1993 Oral Communication, July 22, 1993, Reno, NV

Reference (Deposit): Arehart, G.B., Foland, K.A., Naeser, C.W., and Kesler, S.E., 1993, 40Ar/39Ar, K/Ar, and Fission Track Geochronology of Sediment-Hosted Disseminated Gold Deposits at Post-Betze, Carlin Trend, Northeastern Nevada; Economic Geology, v. 88, no. 3, P. 622-646

Reference (Deposit): Arehart, G. B., Eldridge, C.S., Chryssoulis, S.L., Kesler, S.E., 1993, Ion Microprobe Determination of Sulfur Isotope Variations in Sulfides from the Post/Betze Sediment-Hosted Disseminated Gold Deposit, Nevada, USA, Geochimica et Cosmochimica Acta, v.57, pp.1505-1519

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): Thompson, Tommy, Teal, Lewis, and Meeuwig, Richard, editors, 2002, Gold Deposits of the Carlin Trend, NBMG Bulll. 111.

Reference (Deposit): Chris H. Clode, Steven R. Grusing, Ivan M. Johnston, and Dean G. Heitt, 2002, Geology of the Deep Star Gold Deposit, in Gold Deposits of the Carlin Trend, NBMG Bull. 111.

Reference (Deposit): LONG AND OTHERS, 1998

Reference (Deposit): Bonham, H.L., 1988, Bulk-Mineable Precious-Metal Deposits, in, The Nevada Mineral Industry, 1987, Nevada Bureau of Mines and Geology MI-1987

Reference (Deposit): Bonham, H.L., 1986, Bulk-Mineable Precious-Metal Deposits and Prospects, Nevada Bureau of Mines and Geology Map 91

Reference (Deposit): Bonham, H.L., 1991, Bulk-Mineable Precious-Metal Deposits and Prospects, Nevada Bureau of Mines and Geology Map 91, 3rd ed.

Reference (Deposit): Environmental Assessment, 1987, Nevada Bureau of Mines and Geology Files

Reference (Deposit): Nevada Bureau of Mines and Geology Mining District File 115, Numerous Press Clippings

Reference (Deposit): Lauha, E.A., and Bettles, K.H., 1993, A Geologic Comparison of the Post/Betze and Purple Vein Deposits of the Goldstrike and Meikle Mines, Nevada, SME Preprint 93-170, presented at SME Annual Meeting, Reno, NV, Feb. 15-18, 1993

Reference (Deposit): Bonham, H.L., and Hess, R.H., 1990, Bulk-Mineable Precious-Metal Deposits, in The Nevada Mineral Industry, 1989, Nevada Bureau of Mines and Geology MI-1989, p. 21

Reference (Deposit): Bonham, H.L., 1989, Bulk-Mineable Precious-Metal Deposits, in The Nevada Mineral Industry, 1988, Nevada Bureau of Mines and Geology MI-1988, p.21

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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.