Nixon Fork

Mine, Probably inactive

Alternative names

Mespelt
Crystal
Garnet Extension
Mespelt Inclined Shaft
Recreation
Keen
Twin Shafts
Mespelt Main Shaft
Garnet Trench
Parsons and Strand
Southern Cross

Commodities and mineralogy

Geographic location

Quadrangle map, 1:250,000-scale MD
Quadrangle map, 1:63,360-scale A-4
Latitude 63.2381
Longitude -154.7759
Nearby scientific data Find additional scientific data near this location
Location and accuracy The main portal of the Nixon Fork Mine is near the head of Crystal Gulch about 0.2 mile north of the center of section 13, T. 26 S., R. 21 E., of the Kateel River Meridian. The location is accurate to within 500 feet.

Geologic setting

Geologic description

The Nixon Fork deposit was first staked in 1917 and was mined intermittently from 1918 to 1964, notably by the Yukon-Treadwell company and by E.M. Whalen, from several shafts, open pits, and trenches (Mertie, 1936, Herreid, 1966, Wallis and Rennie, 2005, Postle and others, 2006). The total production during this period is estimated to be 42,200 ounces of gold, 11,281 ounces of silver, and 41,400 pounds of copper from ore that averaged about 1.5 ounce of gold per ton. Much of this production came from ore bodies in the vicinity of this site near the head of Crystal Gulch but at least some came from the nearby Whalen Shaft (MD071) and from the glory hole near it.
The property was explored by Battle Mountain Gold from 1984 to 1988 and by the Nixon Fork Joint Venture/Central Alaska Gold from 1989 to 1993. From 1985 to 1998, 719 surface and underground, reverse circulation and core holes were drilled that totaled 63,093 meters. The deposit was mined by Nevada Goldfields Inc. from 1995 to 1999, when they filed for bankruptcy and the property reverted to its owners. They produced 137,749 ounces of gold and 2,145,826 pounds of copper from 122,391 tons of ore with a 'reconciled' grade of 42 grams of gold per tonne.
St. Andrew Goldfields Ltd. leased the property in 2003, did extensive surface and underground drilling, drove several spiral declines on the ore bodies they defined, and built a 200-ton-per-day mill. They began mining in late 2006 and produced their first gold in January 2007 (St. Andrew Goldfields Ltd., 2009). In the first nine months of 2007, they produced 18,105 tons of ore with a grade of 17.1 grams of gold per ton. Production was suspended in October 2007 to better define the ore bodies as the production was lower than anticipated from their reserve estimates.
In February, 2009, Fire River Gold (2010) acquired the property and in early 2010 they were engaged in a major program of re-logging and reanalyzing the surface and drill samples from the previous operators, mapping, and new drilling to define the deposit.
The Nixon Fork Mine consists of several classic gold-copper, epidote-diopside-garnet skarn deposits, generally within 10 to 150 meters of the periphery of a Cretaceous (68 to 70 Ma) quartz monzonite to granodiorite stock about 3 by 5 kilometers in outcrop area (Moll and others, 1981, Bundtzen and Miller, 1997, Wallis and Rennie, 2005). The stock intrudes the Ordovician Telsitna Formation, a 2,000-meter-thick sequence of limestone and dolomite, and Cretaceous calcareous sandstone and shale. Both the quartz monzonite and the host rocks are cut by late, quartz-feldspar and quartz porphyry dikes.
At least 6 ore bodies are known along about a mile of the west contact of the stock near Crystal Gulch and several more are suspected from surface sampling (Wallis and Rennie, 2005). Five of these were mined from 1995 to 1998. The ore bodies are irregular and complex, often with branching arms, but are roughly pipelike, dip steeply, and follow or parallel the border of the stock at depth. In plan, the ore bodies typically are about 4 meters by 20 to 30 meters in area and extend down dip as much as several hundred meters, sometimes more. They are typically associated with epidote-diopside-garnet skarn near carbonate rocks or hornfels near sandstone and shale. Both exoskarn and endoskarn are present. Most of the ore minerals and skarn are in exoskarn 10 to 30 feet into the marble front. Minor mineralized endoskarn occurs within satellite bodies of monzonite; however, most of this mineralization is not ore grade. The main ore minerals are pyrrhotite, chalcopyrite, pyrite, and native gold; minor bornite and chalcocite are known. The quartz monzonite is sericitized and argillized near the mineralization and some of the ore bodies are oxidized to a depth of 160 meters. However, two of the major ore bodies, the Crystal and Garnet Extension, show little sign of oxidization to the surface.
In 2006, Postle and others (2006) estimated the resources and reserves of the Nikon Fork Mine for St Andrew Gold Fields Ltd. These are: 1) a measured resource of 23,400 tonnes with a grade of 36.8 grams of gold per tonne; 2) an indicated resource of 126,000 tonnes with a grade of 21.6 grams of gold per tonne; 3) an inferred resource of 93,000 tonnes with a grade of 15.5 grams of gold per tonne; 4) a proven reserve of 47,000 tons with a grade of 34.05 grams of gold per tonne; and 5) a probable reserve of 137,500 tonnes with a grade of 18.6 grams of gold per tonne. However, when mining took place from late 2006 to late 2007, the production fell short of the estimates. In early 2010, Fire River Gold was engaged in a major program to better define the reserves and resources.
In Fall of 2010, Fire River released an updated mineral resource estimate (Fire River Gold Corp., 2010b). In July 2011, Fire River started up the Nixon Fork Mill (Fire River Gold, 2011). There was ongoing drilling, mining, and milling in 2012 and early 2013 (Fire River Gold Corp., 2013).
Geologic map unit (-154.77822451835, 63.2374924667591)
Mineral deposit model Copper-gold skarn (Cox and Singer, 1986; model 18b)
Mineral deposit model number 18b
Age of mineralization Late Cretaceous based on 68 to 70 Ma, isotopic age of quartz monzonite adjacent to the skarn ore bodies (Moll and others, 1981, Bundtzen and Miller, 1997, Wallis and Rennie, 2005).
Alteration of deposit Extensive development of endoskarn, exoskarn, and hornfels that is genetically related to the mineralization. Quartz monzonite is sericitized and argillized near the mineralization and some of the ore bodies are oxidized up to a depth of 160 meters (Moll and others, 1981, Bundtzen and Miller, 1997). Other evidence of alteration includes weak argillic alteration around narrow sulfide quartz veins and broad zones of propylitic alteration are present in the quartz monzonite. Late felsic dikes may exhibit silicification overprinted on the argillic alteration (Wallis and Rennie, 2005).

Production and reserves

Workings or exploration
The Nixon Fork deposit was first staked in 1917 and was mined intermittently from 1918 to 1964, notably by the Yukon-Treadwell company and by E.M. Whalen, from several shafts, open pits, and trenches (Mertie, 1936, Herreid, 1966, Wallis and Rennie, 2005, Postle and others, 2006).
The property was explored by Battle Mountain Gold from 1984 to 1988 and by the Nixon Fork Joint Venture/Central Alaska Gold from 1989 to 1993. From 1985 to 1998, 719 surface and underground, reverse circulation and core holes were drilled that totaled 63,093 meters. The deposit was mined by Nevada Goldfields Inc. from 1995 to 1999, when they filed for bankruptcy and the property reverted to its owners.
St. Andrew Goldfields Ltd. leased the property in 2003, did extensive surface and underground drilling, drove several spiral declines on the ore bodies they defined, and built a 200-ton-per-day mill. They began mining in late 2006 and produced their first gold in January 2007 (St. Andrew Goldfields Ltd., 2009). Mining was suspended in October 2007 to better define the ore bodies as the production was lower than anticipated from their reserve estimates.
In February, 2009, Fire River Gold (2010) acquired the property and in early 2010, they were engaged in a major program of re-logging and reanalyzing the surface and drill samples from the previous operators, mapping, and new drilling to define the deposit.
In Fall of 2010, Fire River released an updated mineral resource estimate (Fire River Gold Corp., 2010b). In July 2011, Fire River started up the Nixon Fork Mill (Fire River Gold, 2011). There was ongoing drilling, mining, and milling in 2012 and early 2013 (Fire River Gold Corp., 2013).
Indication of production Yes; medium
Reserve estimates
In 2006, Postle and others (2006) estimated the resources and reserves of the Nikon Fork Mine for St Andrew Gold Fields Ltd. These are: 1) a measured resource of 23,400 tonnes with a grade of 36.8 grams of gold per tonne; 2) an indicated resource of 126,000 tonnes with a grade of 21.6 grams of gold per tonne; 3) an inferred resource of 93,000 tonnes with a grade of 15.5 grams of gold per tonne; 4) a proven reserve of 47,000 tons with a grade of 34.05 grams of gold per tonne; and 5) a probable reserve of 137,500 tonnes with a grade of 18.6 grams of gold per tonne. However, when mining took place from late 2006 to late 2007, the production fell short of the estimates. In early 2010, Fire River Gold was engaged in a major program to better define the reserves and resources.
In December 2011, Fire River released an updated resource estimate based on 2010 and 2011 drilling results. These are: 1) an indicated resource of 129,060 tonnes with a grade of 24.9 grams of gold per tonne in the mines plus 2) an indicated resource of 92,000 tonnes with a grade of 7.9 grams of gold per tonne in the tailings for 3) a total indicated resource of 3,941,067 grams of contained gold; 4) an inferred resource of 53,980 tonnes with a grade of 28.0 grams of gold per tonne in the mines plus 5) an inferred resource of 48,000 tonnes with a grade of 7.4 grams of gold per tonne in the tailings for 6) an inferred resource of 1,863,681 grams of contained gold (Fire River Gold Corp., 2011).
Production notes
The Nixon Fork deposit was first staked in 1917 and was mined intermittently from 1918 to 1964, notably by the Yukon-Treadwell company and E.M. Whalen, from several shafts, open pits, and trenches (Mertie, 1936, Herreid, 1966, Wallis and Rennie, 2005). The total production during this period is estimated to be 42,200 ounces of gold, 11,281 ounces of silver, and 41,400 pounds of copper, from ore that averaged about 1.5 ounce of gold per ton. Much of this production came from ore bodies in the vicinity of Crystal Gulch. But at least some came from the Whalen Shaft (MD071), about a mile south, and from the glory hole near it.
The deposit was mined by Nevada Goldfields Inc. from 1995 to 1999 when they filed for bankruptcy. They produced 137,749 ounces of gold and 2,145,826 pounds of copper from 122,391 tons of ore with a 'reconciled' grade of 42 grams of gold per ton. In the first nine months of 2007, St Andrew Goldfields produced 18,105 tons of ore with a grade of 17.1 grams of gold per ton. Production was suspended in October 2007.

Additional comments

In June 2013, Fire River announced they were suspending operations and placing the mine into care and maintenance mode (Fire River Gold Corp., 2013). In 2014, Fire River announced they defaulted on their credit agreement terms with Waterton Global Value, L.P., and that Waterton has taken full and unrestricted ownership of the Nixon Fork Gold Mine (Fire River Gold Corp., 2014).

References

MRDS Number A012420

References

Bundtzen, T.K., and Miller, M.L., 1997, Precious metals associated with Late Cretaceous-early Tertiary igneous rocks of southwestern Alaska, in Goldfarb, R.J., and Miller, L.D., eds., Mineral Deposits of Alaska: Economic Geology Monograph 9, p. 242-286.
Fire River Gold Corp., 2010a, Nixon Fork overview: http://www.firerivergold.com/s/NixonFork.asp (as of March 2, 2010).
Fire River Gold Corp., 2010b, Fire River Gold Announces Mineral; Resource Estimate for the Nixon Fork Gold Mine, Alaska: http://www.firerivergold.com/i/pdf/100610FAU.pdf (as of July 14, 2014).
Fire River Gold Corp., 2011, Fire River Gold Corp. Provides Updated Resource Estimate: http://www.firerivergold.com/i/pdf/FAU211211b.pdf (as of July 14, 2014).
Fire River Gold Corp., 2011, Fire River Gold Starts Up the Nixon Fork Mill: http://www.firerivergold.com/i/pdf/070511FAU.pdf (as of July 14, 2014).
Fire River Gold Corp., 2013, Fire River Gold Corp. provides operations update: http://www.firerivergold.com/i/pdf/FAU280313.pdf (as of July 14, 2014).
Fire River Gold Corp., 2013, Fire River Gold Suspends Operations: http://www.firerivergold.com/i/pdf/FAU280613.pdf (as of July 14, 2014).
Fire River Gold Corp., 2014, Fire River Announces Waterton takes Ownership of Nixon Fork Gold Mine: http://www.firerivergold.com/i/pdf/FAU-pr-July-7-2014.pdf (as of July 14, 2014).
Freeman, Larry, 1996, A progress report on the Nixon Fork underground gold mine, McGrath-McKinley district, Alaska [abs]: Abstract preprint of the 15th Biennial Conference on Alaskan Mining, Alaska Miners Association, Fairbanks, Alaska, p. 36.
Newberry, R.J., Allegro, G.L., Cutler, S.E., Hagen-Levelle, D.D., Adams, D.D., Nicholson, L.C., Weglarz, T.B., Bakke, A.A., Clautice, K.H., Coulter, G.A., Ford, M.J., Myers, G.L., and Szumigala, D.J., 1997, Skarn deposits of Alaska, in Goldfarb, R.J., and Miller, L.D., eds., Mineral Deposits of Alaska: Economic Geology Monograph 9, p. 355-395.
Postle, John, Scott, Kevin, and Wallis, C.S., 2006, Technical report on the Nixon Fork project Alaska, U.S.A.: Technical report prepared for St. Andrew Goldfields Ltd., 98 p. (posted on www.sedar.com, October 4, 2006).
St Andrew Goldfields Ltd., 2009, Nixon Fork Mine: was available on the Internet as of March 11, 2009.
Wallis, C.S., and Rennie, E.W., 2005, Technical report on the Nixon Fork project, Alaska: Technical Report prepared for St. Andrew Goldfields Ltd., 78 p. (posted on www.sedar.com, October 4, 2006).
Wallis, C.S., Rennie, D.W., and Hendry, J.W., 2003, Report on the Nixon Fork project, Alaska: Technical Report prepared for St. Andrew Goldfields Ltd., 65 p. (posted on www.sedar.com, September 17, 2003).
Reporters Bundtzen, T.K. (Pacific Rim Geological Consulting); D.J. Grybeck (Contractor, U.S. Geological Survey); V.C. Zinno (Alaska Earth Sciences, Inc.)
Last report date 12/2/2014