Mule Canyon Mine

Site Name

Primary: Mule Canyon Mine
Secondary: North Zone
Secondary: Ashcraft Zone
Secondary: South Zone
Secondary: Main Zone
Secondary: West Zone
Secondary: Section 9 Zone

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Commodity

Primary: Silver
Primary: Gold
Tertiary: Arsenic
Tertiary: Zinc
Tertiary: Lead
Tertiary: Copper
Tertiary: Selenium
Tertiary: Mercury
Tertiary: Antimony

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Location

State: Nevada
County: Lander
District: Argenta District

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Land Status

Land ownership: BLM Administrative Area
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.
Administrative Organization: Battle Mountain BLM District

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Holdings

Not available

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Workings

Not available

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Ownership

Owner Name: Newmont Gold

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Production

Not available

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Deposit

Record Type: Site
Operation Category: Producer
Deposit Type: Hot Spring
Operation Type: Surface
Discovery Year: 1986
Years of Production:
Organization:
Significant: Y
Deposit Size: M

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Physiography

Not available

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Mineral Deposit Model

Model Name: Hot-spring Au-Ag

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Orebody

Form: Orebodies are tabular to lenticular in form, following steeply-dipping NNW structures.

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Structure

Type: L
Description: The Mule Canyon deposit is localized along NNW-trending faults that define the western margin of a graben that is part of the Northern Nevada rift zone, developed contemporaneously with Miocene volcanism.

Type: R
Description: The NNW-trending Oregon-Nevada lineament is a narrow, deep-seated crustal flaw exhibited in this area by a diking event that may have provided the feeders for the ore-host volcanic rocks of the deposit.

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Alterations

Alteration Type: L
Alteration Text: Alteration consists predominantly of pervasive argillization and to a lesser extent, silicification. Alteration is laterally zoned and consists of an intensely altered illite-smectite-quartz-adularia core zone surrounded by an iron-rich smectite-nontronite zone, with an outer propylitic halo of calcite-chlorite-minor smectite alteration.

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Rocks

Role: Associated
Age Type: Associated Rock Unit
Age Young: Ordovician
Age Old: Late Cambrian

Role: Associated
Age Type: Associated Rock Unit
Age Young: Silurian

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

Name: Pyroclastic Rock
Role: Host
Age Type: Host Rock
Age in Years: 16.000000+-
Age Young: Early Miocene

Name: Pyroclastic Rock
Role: Host
Age Type: Host Rock
Age in Years: 15.000000+-
Age Young: Middle Miocene

Name: Tuff
Role: Host
Description: lapilli air-fall
Age Type: Host Rock
Age in Years: 16.000000+-
Age Young: Early Miocene

Name: Tuff
Role: Host
Description: lapilli air-fall
Age Type: Host Rock
Age in Years: 15.000000+-
Age Young: Middle Miocene

Name: Andesite
Role: Host
Description: basaltic
Age Type: Host Rock
Age in Years: 16.000000+-
Age Young: Early Miocene

Name: Andesite
Role: Host
Description: basaltic
Age Type: Host Rock
Age in Years: 15.000000+-
Age Young: Middle Miocene

Name: Basalt
Role: Host
Age Type: Host Rock
Age in Years: 16.000000+-
Age Young: Early Miocene

Name: Basalt
Role: Host
Age Type: Host Rock
Age in Years: 15.000000+-
Age Young: Middle Miocene

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Analytical Data

Not available

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Materials

Ore: Electrum
Ore: Calcite
Ore: Marcasite
Ore: Pyrite
Ore: Arsenopyrite
Ore: Adularia
Ore: Polybasite
Ore: Naumannite
Ore: Aguilarite
Ore: Acanthite
Ore: Argentite
Ore: Pyrargyrite
Ore: Tetrahedrite
Ore: Arsenopyrite
Ore: Zeolite
Gangue: Quartz

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Comments

Comment (Development): Goldfields Mining Company made the initial discovery in 1986 as a result of a grassroots geochemical exploration program. In 1991, Hanson Natural Resources Company reported that drilling on its Mule Canyon gold deposit had identified six orebodies containing reserves of 8.5 million tons of ore with an average grade of 0.136 opt gold (1.15 million ounces of gold). A test adit was driven in the west zone orebody in fall of 1991 for the purpose of collecting bulk samples for metallurgical tests, which provided the basis to justify feasibility studies on the deposit and to begin the permitting process to develop it into a gold mine. The property was acquired by Santa Fe Pacific Gold Company prior to 1995, at which time reserves were listed as 4.22 million tons oxide ore grading 0.058opt gold and 5.78 million tons sulfide ore averaging 0.145 opt. In early 1996, Santa Fe that drilling was continuing on the project to identify additional mineralization. Newmont Gold Company acquired the property as part of its takeover of Santa Fe in early 1997 and planned to ship the higher-grade sulfide ore to Twin Creeks for autoclave processing. The remaining lower grade ore would be heap-leached on site with the resulting gold-loaded carbon to be shipped to Lone Tree Mine for processing. As a result of this reconfiguration, the need for construction of an autoclave at Mule Canyon was eliminated. Mining activity at Mule Canyon began on Oct. 29, 1996 with trucking of Mule Canyon's high grade ore to the Lone Tree processing facility in early November, and the first Mule Canyon gold was included in gold dore poured at Lone Tree on November 22, 1996. Mule Canyon 1997 production was expected to be about 100,000 ounces annually with cash costs in the range of $240 to $250 per ounce; annual production was expected to increase later in Mule Canyon's projected mine life of eight years.

Comment (Economic Factors): Production began in 1996, at which time reserves were 15,918,000 short tons grading 0.09 opt (45 metric tonnes Au). Other sources listed 1996 reserves as 9 million tons grading 0.112 opt gold. About 700,000 additional ounces of gold contained in mineralized material, not included in reserves, have been identified at Mule Canyon.

Comment (Geology): The gold ore is hosted by basalt and basaltic andesite. Specifically, the ore host rocks are a lapilli ash tuff (probably air-fall in origin) up to 300 feet thick, with intermixed pyroclastic flow rocks. Welding of both units was partial and spotty. The ore-hosts are overlain by a thick package of finer-grained effusive volcanic rocks.

Comment (Location): UTM location is given for an area centrally located within the currently productive ore zones of the mine.

Comment (Workings): Mine workings consist of several open pits developed on the different orebodies, as well as crushing and heap leach facilities.

Comment (Commodity): Gangue Materials: QUARTZ, ADULARIA, ARSENOPYRITE, PYRITE, MARCASITE, CALCITE, ZEOLITES

Comment (Commodity): Ore Materials: electrum, auriferous arsenopyrite, tetrahedrite, pyrargyrite, argentite, acanthite, aguilarite, naumannite, polybasite

Comment (Deposit): The deposit is composed of six orebodies called the North, Ashcraft, South, Main, West, and Section 9 zones. The six discrete orebodies are aligned along a N-S-trending zone extending more than 2.5 miles. The ore zones are controlled primarily by NNW-trending faults which provided the conduits for ascending hydrothermal solutions to enter the porous host Miocene age basalts and andesites. These NNW-trending faults define the western margin of a graben that is part of the Northern Nevada rift zone, developed contemporaneously with Miocene volcanism. The hydrothermal activity at Mule Canyon is thought to have started at about the same time as the down-dropping of the NNW-trending graben. A finer-grained cap rock appears to have acted as a barrier and may have trapped ore-forming fluids. Episodic hydrothermal brecciation and hydrothermal fracturing events are recognized and probably aided in the development of ore-grade mineralization. Trace amounts of telluride minerals, including petzite, hessite, stuetzite, and altaite were identified in the ore, as well as trace amounts of stibnite, cinnabar, pyrrhotite, chalcopyrite, sphalerite, covellite, native copper and galena. The trace element geochemistry is typical of upper level hot spring precious metal systems. The Mule Canyon deposit is located about 3.5 miles west of the Beowawe geothermal field and may represent a fossil analog of this system.

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References

Reference (Deposit): NBMG MI-1995

Reference (Deposit): NBMG MI-1996

Reference (Deposit): Santa Fe Pacific Gold, 1996 SEC Form 10K

Reference (Deposit): The Denver Mining Record, 12/11/96

Reference (Deposit): Pay Dirt, 2/1/96, 4/1/96

Reference (Deposit): Engineering and Mining Journal,10/1/95

Reference (Deposit): Long, K.R., DeYoung, J.H., Jr., and Ludington, S.D., 1998, Significant deposits of gold, silver, copper, lead, and zinc in the United States: U.S. Geological Survey Open-File Report 90-206A, 33 p.; 98-206B. one 3.5 inch diskette.

Reference (Deposit): Thomson and others, 1993, Geology and geochemistry of the Mule Canyon gold deposit, Lander County, NV, SME Preprint

Reference (Deposit): NBMG MI-1992

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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.