Big Hurrah

Mine, Active

Commodities and mineralogy

Main commodities Au
Other commodities Ag; Cu; W; Zn
Ore minerals arsenopyrite; chalcopyrite; electrum; gold; pyrite; scheelite; sphalerite
Gangue minerals albite; carbonate; quartz; sericite

Geographic location

Quadrangle map, 1:250,000-scale SO
Quadrangle map, 1:63,360-scale C-5
Latitude 64.6514
Longitude -164.2398
Nearby scientific data Find additional scientific data near this location
Location and accuracy The Big Hurrah mine is located on the south side of Big Hurrah Creek (SO022) and the east side of Little Hurrah Creek at an elevation of about 275 feet. It is about 1/4 mile southeast of the confluence of Little and Big Hurrah creeks. It is locality 17 of Cobb (1972, MF 445; 1978, OF 78-181).

Geologic setting

Geologic description

The Big Hurrah mine has been the most productive lode gold mine on the Seward Peninsula to date. Gold-quartz veins in slaty graphitic schist produced about 27,000 ounces of gold (Read and Meinert, 1986) primarily between 1903 and 1907, when a 20-stamp mill was in operation (Smith, 1910). The ore that was mined averaged a little less than 1 ounce of gold per ton (Cobb, 1978); six samples collected underground in 1952 from the 70 foot level contained 0.08 to 5.2 ounces of gold per ton and 0.5 to 17.2 ounces of silver per ton (Asher, 1969). The mill tailings were cyanided and there were attempts to restart underground mining in the 1950s. A fire and unstable ground prevented further underground work and all workings are now (2007) flooded. However, considerable core drilling and surface trenching has taken place in recent years, primarily in the 1980s.
NovaGold Resources, Inc. (2006) acquired the Big Hurrah deposit in mid-2004. In 2004 and 2005, they drilled a total of 17,750 meters in 292 core and rotary holes. The objective was to define an open-pittable resource of 100,000 to 200,000 ounces of gold in ore that contains 5 to 7 grams of gold per ton. Production of this resource is being evaluated as part of the Rock Creek (NM207) feasibility study. In this scenario, the Big Hurrah ore would be trucked 48 miles to the proposed Rock Creek mill for processing. As of March 28, 2007, NovaGold (2007) listed a measured and indicated resource in the Big Hurrah mine as 1.8 millions tons of ore with a grade of 4.61 grams of gold per metric ton; there was an additional inferred resource of 0.6 million tons of material with a grade of 3.05 grams of gold per metric ton.
Read and Meinert (1986) describe five types of veins: 1) quartz +/- carbonate lenses, 2 to 7 centimeters thick, locally contain minor sphalerite, chlorite and arsenopyrite; 2) quartz, carbonate, pyrite, sphalerite and chalcopyrite form tabular veins 2 to 5 millimeters thick; 3) ribbon quartz veins up to 4 meters wide that average about 0.5 meters wide occupy NW-trending faults and contain more than 90 percent quartz, dolomite, albite, sericite, scheelite, arsenopyrite, pyrite and native gold; the total sulfide content is less than 2 to 3 percent and scheelite is less than 1 percent; 4) quartz-albite +/- arsenopyrite veins 5 to 25 centimeters wide contain up to 25 percent albite, up to 20 percent arsenopyrite and minor gold; thought to be syngenetic; 5) post-mineralization carbonate-quartz veinlets 2 to 3 millimeters thick that cut all other vein types. Coats (1944) estimated that the scheelite content of gold ore that remained in the bins was 0.25 percent by volume. Some veins are up to several hundred feet long; the larger veins strike northwest and dip southwest (Asher, 1969, DGGS R33). Fluid inclusion data from these veins indicate multiple generations of fluids; early veins contain CO2-CH4 and later veins are rich in H2O-NaCl. Homogenization temperatures vary from 390 to 90 degrees C. The available data suggests that the gold-bearing fluids were produced by regional metamorphic processes. The country rock is part of a lower Paleozoic metasedimentary assemblage (Sainsbury and others, 1972; Till and others, 1986) that includes a distinctive black, very fine-grained, graphitic schist that early workers called the Hurrah Slate.
The Big Hurrah veins are probably similar in age to some other gold-quartz veins of southern Seward Peninsula. The other southern Seward Peninsula lode gold deposits formed as a result of mid-Cretaceous metamorphism (Apodoca, 1994; Ford, 1993, Ford and Snee, 1996; Goldfarb and others, 1997) that accompanied regional extension (Miller and Hudson, 1991) and crustal melting (Hudson, 1994). This higher temperature metamorphism was superimposed on high pressure/low temperature metamorphic rocks of the region.
Geologic map unit (-164.242406418876, 64.65065857411)
Mineral deposit model Gold-quartz vein in metamorphic rocks; low sulfide-Au quartz vein (Cox and Singer, 1986; model 36a).
Mineral deposit model number 36a
Age of mineralization Cretaceous?
Alteration of deposit Silicification, carbonatization, and development of quartz-carbonate stockworks.

Production and reserves

Workings or exploration
A 60-degree inclined shaft extended to the 250 foot level; there are about 1,800 feet of lateral workings developed off it on the 70, 150, and 250 foot-levels. In 1954, a 105-foot-long sublevel was driven at 20 feet below the 150-East level (Asher, 1969, DGGS R33). There are also numerous surface prospecting pits and trenches on the property.
NovaGold Resources, Inc. acquired the Big Hurrah deposit in mid-2004. In 2004 and 2005, they drilled a total of 17,750 meters in 292 core and rotary holes. The objective is to define an open-pittable resource of 100,000 to 200,000 ounces of gold in ore that contains 5 to 7 grams of gold per ton. Production of this resource is being evaluated as part of the Rock Creek (NM207) feasibility study. In this scenario, the Big Hurrah ore would be trucked 48 miles to the proposed Rock Creek mill for processing.
Indication of production Yes; small
Reserve estimates As of March 28, 2007, NovaGold (2007) listed a measured and indicated resource in the Big Hurrah mine as 1.8 millions tons of ore with a grade of 4.61 grams of gold per metric ton; there was an additional inferred resource of 0.6 milllion tons of material with a grade of 3.05 grams of gold per metric ton.
Production notes The Big Hurrah mine is the only lode gold mine on Seward Peninsula. The gold-quartz veins in slaty graphitic schist produced about 27,000 ounces of gold (Read and Meinert, 1986), primarily between 1903 and 1907, when a 20-stamp mill was in operation (Smith, 1910).

References

MRDS Number A010654; A012593; D002598

References

Apodoca, L.E., 1994, Genesis of lode gold deposits of the Rock Creek area, Nome mining district, Seward Peninsula, Alaska: Boulder, Colorado, University of Colorado, Ph.D. dissertation, 208 p.
Ford, R.C., 1993, Geology, geochemistry, and age of gold lodes at Bluff and Mt. Distin, Seward Peninsula, Alaska: Golden, Colorado School of Mines, Ph.D. dissertation, 302 p.
Ford, R.C., and Snee, L.W., 1996, 40Ar/39Ar thermochronology of white mica from the Nome district, Alaska--The first ages of lode sources to placer gold deposits in the Seward Peninsula: Economic Geology, v. 91, p. 213-220.
Goldfarb, R.J., Miller, L.D., Leach, D.L., and Snee, L.W, 1997, Gold deposits in metamorphic rocks in Alaska, in Goldfarb, R.J., and Miller, L.D., eds., Mineral Deposits of Alaska: Economic Geology Monograph 9, p. 151-190.
Hudson, T.L., 1994, Crustal melting events in Alaska, in Plafker, G., and Berg, H. C., eds., The Geology of Alaska: Geological Society of America, DNAG, The Geology of North America, Vol. G-1, p. 657-670.
NovaGold Resources Inc., 2006 (Rock Creek): www.novagold.net/s/NewsReleases.asp?ReportID=118197&_Type=News-Releases&_Title=Update-on-Rock-Creek-Gold-Mine-Development-in-Nome-Alask (as of April, 2007).
NovaGold Resources Inc., 2007 (Reserve): (http://www.novagold.net/i/pdf/NGReserve_ResourceTable.pdf (March, 2007).
Read, J.J., and Meinert, L.D., 1986, Gold-bearing quartz vein mineralization at the Big Hurrah mine, Seward Peninsula, Alaska: Economic Geology, v. 81, p. 1760-1774.
Reporters Travis L. Hudson (Applied Geology, Inc.)
Last report date 10/10/2005