Limousine Butte Gold Deposits

Site Name

Primary: Limousine Butte Gold Deposits
Secondary: Resurrection Ridge (part)

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Commodity

Primary: Silver
Primary: Gold
Tertiary: Tungsten
Tertiary: Copper
Tertiary: Bismuth
Tertiary: Arsenic

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Location

State: Nevada
County: White Pine
District: Cherry Creek 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: Ely BLM administrative district

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Holdings

Not available

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Workings

Not available

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Ownership

Owner Name: Nevada Pacific Gold (US) Inc.
Info Year: 2004

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Production

Not available

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Deposit

Record Type: Site
Operation Category: Past Producer
Deposit Type: Porphyry copper-gold, skarn-related, sediment-hosted gold
Operation Type: Unknown
Years of Production:
Organization:
Significant: Y
Deposit Size: S

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Physiography

Not available

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Mineral Deposit Model

Model Name: Sediment-hosted Au
Model Name: Porphyry Cu, skarn-related
Model Name: Skarn Au

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Orebody

Form: irregular

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Structure

Type: L
Description: Black Metals Fault zone and other steeply-dipping fault zones.

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Alterations

Alteration Type: L
Alteration Text: Rhyolite porphyry is argillized, adjacent sedimentary rocks are skarn-altered and jasperoidized.

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Rocks

Role: Associated
Age Type: Associated Rock Unit
Age in Years: 159.000000+-
Age Young: Late Jurassic

Name: Limestone
Role: Host
Age Type: Host Rock
Age Young: Early Permian
Age Old: Late Mississippian

Name: Shale
Role: Host
Age Type: Host Rock
Age Young: Early Mississippian
Age Old: Late Devonian

Name: Skarn (Tactite)
Role: Host
Age Type: Host Rock
Age Young: Pennsylvanian
Age Old: Devonian

Name: Porphyry
Role: Host
Description: argillized rhyolite
Age Type: Host Rock
Age Young: Cretaceous

Name: Rhyolite
Role: Host
Description: argillized porphyry
Age Type: Host Rock
Age Young: Cretaceous

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Analytical Data

Not available

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Materials

Ore: Gold

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Comments

Comment (Commodity): Ore Materials: gold

Comment (Deposit): The property consists of a hydrothermal gold system that exhibits alteration features related to sediment/structure hosted gold deposits found elsewhere in Nevada. Mineralization at the Limousine Butte property consists of disseminated, structurally controlled and skarn hosted gold deposits related to a large mineralized porphyry complex located beneath the valley floor. In addition to the gold potential, a substantive copper/gold porphyry is present at Limousine Butte. Prospect drilling (15 holes) in the 1960's and 70's indicates that it has minimum dimensions of 1.5 miles by 0.75 miles. The quartz porphyry intrusive with an associated sulfide-alteration system is centered below the western portion of the property and has altered and mineralized extensive portions of westerly dipping Mississipian sedimentary rocks. Broad zones of silicification, brecciation and hornfel/skarns are developed within shales and carbonates near the quartz porphyry intrusive. Jasperoid alteration is present within the same reactive rocks 4.5 miles to the east where they form outcrops along the range front. Anomalous gold and copper mineralization occurs within and adjacent to the intrusive such as: 1,000 feet grading 0.10 percent copper in hole BV-11 and 701 feet grading 0.019 opt gold in hole BV-10. Relogging of several holes in the porphyry system suggested a late gold system overprint crosscutting and replacing skarn altered sediments and hosted within argillized rhyolite.

Comment (Development): At Nevada Pacific Gold Ltd.'s Limousine Butte project, joint venture partner Newmont Mining Corp. is focusing on six new target areas of hese new targets, located about 5 to 8 miles south of the previously identified discovery areas drilled during earlier exploration campaigns of the joint venture, were identified through exploration work conducted by Newmont, which consisted of a high-definition airborne magnetic/radiometric geophysical survey, ground-based gravity geophysics, detailed geologic mapping, and in excess of 800 rock chip/stream sediment samples. Using all drill-hole information available, Newmont has estimated mineral inventories on five disseminated oxide gold zones identified to date at Limousine Butte. These five zones, located in the central to northern portion of the project, contain in excess of 620,000 oz of gold (estimated at a 0.006 opt Au cutoff and an average grade of drill intercepts above that cutoff).

Comment (Economic Factors): The deposits contain a reported 620,000 ounce gold mineral inventory (2004). In the 1960s, Bear Creek Mining calculated the porphyry to contain a resource of 50 million tons of 0.6% copper.

Comment (Location): This deposit is on the west flank of the Cherry Creek Range at the edge of Butte Valley, but as it has no organized mining district of its own, prospects in this area have in the past sometimes been included in the Cherry Creek District, whose mines lie mostly on the east side of the Cherry Creek Range. 765 unpatented mining claims cover the property.

Comment (Development): Porphyry copper exploration by many exploration companies was carried out in the Limousine Butte project area from the 1950s through the1980s that drilled several zones of low-grade gold and copper mineralization. This work identified porphyry-related gold mineralization up to 0.070 opt Au and skarn style gold mineralization grading up to 0.19 opt Au in drill holes. During the 1980's the Alta Gold-Echo Bay joint venture mined approximately 130,000 ounces of gold from surface jasperiods via heap leach at the Golden Butte Mine adjacent to the northeast portion of the property.Nevada Pacific Gold acquired the property through claim staking in 1997 and began compiling all the historical geologic and geochemical data produced over this forty year period. Gulf Minerals first identified a porphyry/skarn type magnetic signature in Butte Valley with a high-level aeromagnetics survey in the mid-1950s. The Newmont/New Jersey Zinc Joint Venture first drilled the discovery in 1962. Bear Creek Mining later calculated the porphyry to contain a resource of 50 million tons of 0.6% copper which was covered by a 1500 to 2500 foot thick post-mineral slide block. Relogging of several holes in the porphyry system suggested a late gold system overprint crosscutting and replacing skarn altered sediments and hosted within argillized rhyolite. The best intercept in the skarn/porphyry consisted of 701 feet of 0.019 opt gold, in drill hole BV-10. A small gold resource of 91,000 ounces was produced from shale and jasperoid hosted dolomites at the Golden Butte Mine in the north part of the project area by Alta Gold from 1987-1989. Between the Golden Butte mine and the Butte Valley porphyry, several gold anomalies are present in the Paleozoic carbonate and clastic rocks that range in age from the Devonian Pilot Shale to the Pennsylvanian Ely Limestone. Exploration drilling and geologic mapping in the Golden Butte Mine area (Resurrection Ridge) has identified that gold was formed along the edge of an Eocene age volcanic filled graben or possible caldera margin. The graben contact fault is a "feeder fault", containing high-grade gold (30 feet of 0.260 opt) at the shale-dolomite graben fault contact. The strike extension of this fault, and the alteration associated with it, is at least six miles long. On April 1, 1999 Newmont Mining Corporation and NPG entered into a joint venture agreement to explore the Limousine Butte property. By June of 2002, Newmont had spent $1,048,220 on identifying and drilling twenty one sediment hosted gold targets within a 25 square mile area. Drilling by Newmont and NPG to date (2004) has defined six oxide gold mineral inventories containing 39.4 mt grading 0.016 opt gold for a total of 620,000 ounces of gold. In 2002, Newmont elected to sell back its interest in Limousine Butte and presently holds a sliding production royalty of 1.5% to 2.5%. Meanwhile, NPG continues to explore the project area having completed another round of drilling in 2003, intersecting additional high grade (20' @ 0.309 oz/t) and low grade (195' @ 0.05 oz/t) gold mineralization in the Resurrection Ridge area. Drilling is ongoing in spring, 2004.

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References

Reference (Deposit): Nevada Pacific Gold Ltd. website and press releases, 2002-2004.

Reference (Deposit): NBMG MI-2002.

Reference (Deposit): Curt Everson, 2004, Geology and Mineralization of the Limousine Butte gold deposits, White Pine County, Nevada; Geological Society of Nevada presentation and abstract.

Reference (Deposit): Unpublished field observations from NBMG geologists who examined the prospect area in the early 1980s, on file at NBMG.

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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.