Summit

Mine, Active

Commodities and mineralogy

Main commodities Ag; Au
Other commodities As; Cu; Pb; Sb; Sn
Ore minerals arsenopyrite; galena; gold; scorodite; sphalerite; stibnite
Gangue minerals quartz

Geographic location

Quadrangle map, 1:250,000-scale CH
Quadrangle map, 1:63,360-scale C-3
Latitude 67.5387
Longitude -148.1853
Nearby scientific data Find additional scientific data near this location
Location and accuracy The Summit Mine is on the ridge at the head of Big Squaw Creek about 0.6 mile south of Little Squaw Peak. It is at an elevation of about 4,600 feet about 0.5 mile west of the center of section 3, T. 31 N., R. 3 W. The location is accurate.

Geologic setting

Geologic description

Placer gold was discovered in the Chandalar area on Little Squaw Creek (CH039) in 1902 (Barker, and Bundtzen, 2004; Barker, 2007; Barker and others, 2009). By 1909, four quartz veins including the Mikado vein had been discovered and many more were located prior to WWI. Most of the important properties in the district were consolidated by William Sulzer from 1909 to 1941; the Summit Mine was one of the prominent deposits of the Chandalar area and was included. Those properties were taken over in 1946 to form the Little Squaw Mining Company in 1959, which in turn became the Little Squaw Gold Mining Company in 1968. From 1967 to 1999, Little Squaw Gold Mining Company leased some of their Chandalar lode and placer ground for mining and/or exploration to a succession of companies, notably the Chandalar Gold Mining and Milling Company (1967-1971), Noranda Mining (1974-1976), the Chandalar Development Corporation (1980-1983), and Gold Dust Mines (1989-1999). There was some earlier small lode production from the district but the first documented gold produced from the lodes was 870 ounces produced from 1967 to 1971 from the Mikado and Summit mines by the Chandalar Gold Mining and Milling Company. Subsequently, Chandalar Development produced 8,169 ounces of lode gold from the Mikado and Summit Mines but recovery was poor. In 2003, Little Squaw Gold Mining Company and its direct descendent Goldrich Mining Company began an aggressive exploration program for lode and placer deposits over a large block of land that covers almost all of the known deposits in the Chandalar area and as of early 2012, that effort continued (Goldrich Mining Company, 2012).
The geology of the Chandalar area is dominated by a system of west-northwest-trending regional faults including a prominent thrust fault in the southern part of the district and a series of major high-angle faults through the center of the area (Bundtzen and Laird, 2007 [map]; 2007 [83 p.]. These faults separate the rocks into two principal units, a west-northwest-trending Upper Plate unit about 3 miles wide in the center of the area and a Lower Plate unit to the north and south. The contact of the two units is a thrust fault on the south side of the Upper Plate rocks and a high-angle fault on the north side. Most of the Upper Plate rocks consist of Devonian upper-greenschist-facies metamorphic rocks, mainly carbonaceous schist; quartz-chlorite-muscovite schist, schist and phyllite derived from turbidites that comprise the Mikado Phyllite, metamorphosed calcareous sandstone, and quartz-muscovite schist. The Lower Plate rocks consist of Devonian, upper-greenschist-facies metamorphic rocks, mainly metamorphosed volcanic agglomerate, chlorite-rich tuffaceous schist, quartz-mica schist derived from mudstone, mica-quartz schist, and quartzite. Both the Upper and Lower Plate rocks are cut by irregular masses, dikes and sills of greenstone, metagabbro, and metadiorite of unknown age. Most of the mineral deposits in the Chandalar area are in the Upper Plate rocks and the deposits often are along the regional, steep-to-vertical, west-northwest-trending faults. There is an additional conjugate set of north-northeast-trending faults that offset the Upper Plate rocks and at least some of the mineralization may be localized at the intersections of the regional west-northwest-trending faults and the conjugate faults. The rocks in the vicinity of the Summit Mine are mainly coarse- to fine-grained, rhythmically layered schist and phyllite of the Upper Plate.
By 1913, a 54-foot-deep shaft had been sunk on the Summit vein and a short adit driven on a 1.5- to 2.5-foot-thick gold-quartz vein (Maddren, 1913). The vein was exposed for 950 feet in a series of trenches. Numerous samples have been taken over the years by numerous companies of the Summit mineralization. Samples containing more than 1 ounce of gold are common, samples over 10 ounces per ton are not uncommon, and samples with visible gold can be found relatively easily. Heiner and Wolff (1968) report that there was some development work in the 1950s and a small mill was built by Ed Toussaint in 1957 and 1958 at the head of Big Creek to process ore from the Summit vein (Buzzell, 2007). It may not have milled any Summit ore although Barker and others (2008) note that it milled some ore from the Indicate vein (CH042) near the mill. Little Squaw Gold Mining Company drilled the Summit property in 2006 (Barker and others, 2009). Three of the holes intersected quartz veins; the best 5-foot intervals contained 5.71, 16.15, 5.52, and 3.24 parts per million gold. Goldrich Mining Corp. (2011) drilled 3 holes in 2011 that totaled 441 meters. Of the four intercepts 2.1 to 10.7 meters long that contained more than 0.50 grams of gold per tonne, the best was 2.1 meters that contained 1.23 ounces of gold per tonne.
The gold mineralization is localized along the Summit fault which strikes about N70-80W, dips 75-80 degrees north, and is marked by 1 to 6 inches of gray to black gouge (Chip 1970, Barker and Bundtzen, 2004, Barker, 2007; Barker and others, 2009). The rocks in the area are black to gray carbonaceous phyllite and schist of the Mikado Phyllite unit of Bundtzen and Laird (2007a, 2007b) overlain by lighter gray, muscovite, chlorite-quartz schist. Ashworth (1983) described two generations of quartz at the Summit lode. The older generation is coarsely crystalline, massive, white quartz. It is in the hanging wall and is as much as 4 feet wide. It contains less than 5 percent sulfides and little gold. The younger generation pinches and swells; it adjoins the older veins, but typically is in the footwall. It is generally finer grained and contains bands accentuated by smeared graphite and arsenopyrite. Scorodite is common, and free gold occurs as blebs and occasional wires. The veins are offset by near-vertical faults. In contrast to some of the other deposits in the area, e.g., the Little Squaw Mine (CH040), the Summit veins are usually moderately to strongly brecciated. The gold veins in the Chandalar district are considered mesothermal (Barker and Bundtzen, 2004; Barker, 2006; Barker, 2007; Barker and others, 2009) by comparison with similar deposits elsewhere and in consideration of fluid inclusion and oxygen and lead isotope studies of the Chandalar mineralization (Ashworth, 1983; Rose and others, 1988; Gacetta and Church, 1989).
The Chandalar Development Corporation mined the Summit vein from 1980 to 1983 (Barker and Bundtzen, 2004; Barker and others, 2009). They produced 1,347 ounces of gold from 1,401 tons of ore that averaged 1.29 ounces of gold per ton. The gold recovery was poor, apparently because the mill was not designed for the large amount of gouge in the ore.
In 2003, Little Squaw Gold Mining Company estimated that the 'probable resource' of the Summit Mine was 1,375 tons with a grade of 3.52 ounces of gold per ton and a 'possible resource' of 3,165 tons with an average grade of 2.13 ounces per ton (Barker and Bundtzen, 2004). However, the extensive trench and drill data collected during the work begun by Little Squaw Gold Mining Company in 2004 and continued by its successor Goldrich Mining Company indicate that the Summit vein is bordered by a wide aureole of lower grade, sheeting veins and disseminated gold. The high-grade veins that have traditionally been the exploration target may have overlooked the substantial potential in the low grade but large body of mineralization peripheral to the high grade veins (Barker and others, 2009).
Geologic map unit (-148.188032578642, 67.5383176768537)
Mineral deposit model Low-sulfide Au-quartz veins (Cox and Singer, 1986; model 36a).
Mineral deposit model number 36a
Age of mineralization Possibly mid-Cretaceous based on the assertion of Dillon (1982) that the gold-quartz veins of the central Brooks Range are that age. However, there is no definitive data for the age of the veins of the Chandalar area.
Alteration of deposit Oxidation of vein material produced scorodite and limonite.

Production and reserves

Workings or exploration By 1913, a 54-foot-deep shaft had been sunk on the Summit vein and a short adit driven on a 1.5- to 2.5-foot-thick gold-quartz vein (Maddren, 1913). The vein was exposed for 950 feet in a series of trenches. Numerous samples have been taken over the years by numerous companies of the Summit mineralization. Heiner and Wolff (1968) report that there was some development work in the 1950s and a small mill was built by Ed Toussaint in 1957 and 1958 at the head of Big Creek to process ore from the Summit vein (Buzzell, 2007). It may not have milled any Summit ore although Barker and others (2008) note that it milled some ore from the Indicate vein (CH042) near the mill. In addition to much surface sampling, trenching, and mapping, Little Squaw Gold Mining Company drilled the Summit property in 2006 (Barker and others, 2009). Goldrich Mining Corp. (2011) drilled 3 holes that totaled 441 meters in 2011.
Indication of production Undetermined
Reserve estimates In 2003, Little Squaw Gold Mining Company estimated that the 'probable resource' of the Summit Mine was 1,375 tons of material with a grade of 3.52 ounces of gold per ton and a 'possible resource' of 3,165 tons of material with an average grade of 2.13 ounces per ton (Barker and Bundtzen, 2004). However, the extensive trench and drill data collected during the work begun by Little Squaw Gold Mining Company in 2004 and its successor Goldrich Mining Company indicate that the Summit vein is bordered by a wide aureole of lower grade, sheeting veins and disseminated gold. The high-grade veins that have traditionally been the exploration target may have overlooked the substantial potential in the low grade but large body of mineralization peripheral to the high grade veins (Barker and others, 2009).
Production notes The Chandalar Development Corporation mined the Summit vein from 1980 to 1983 (Barker and Bundtzen, 2004; Barker and others, 2009). They produced 1,347 ounces of gold from 1,401 tons of ore that averaged 1.29 ounces of gold per ton. The gold recovery was poor, apparently because the mill was not designed for the large amount of gouge in the mine-run ore.

References

MRDS Number A012561

References

Ashworth, K.K., 1983, Genesis of gold deposits at the Little Squaw mines, Chandalar mining district, Alaska: Bellingham, Western Washington University, M.Sc. thesis, 98 p.
Ashworth, (Lamal) Kate, 1984, Fluid inclusion study of the Eneveloe Vein, Chandalar Mining District: Private Report, Chandalar Development Associates, 8 pages (in files of the Goldrich Mining Company).
Barker, J.C., 2006, Chandalar Mining District, a report of findings and recommendations, 2005: Unpublished report for Little Squaw Gold Mining Company, 93 p. (on Internet at http://www.goldrichmining.com/Files/corporate/2005AnnualReport011906.pdf, as of February 14, 2010).
Barker, J.C., 2007, Chandalar Mining District, Annual Report of findings for 2006; Unpublished report for Little Squaw Gold Mining Company, 124 p. (On the Internet at http://www.goldrichmining.com/Files/chandalar/chandalar_barker_rpt_2007.pdf, as of February 14, 2010).
Barker, J.C., and Bundtzen, T.K., 2004, Gold deposits of the Chandalar Mining District, Northern Alaska: An information review and recommendations: Unpublished report for the Little Squaw Gold Mining Company, 165 p. (in the files of the Goldrich Mining Company).
Barker, J.C., Murray, R.B., Keener, J.O., and Martin, P.L., 2009, Evaluation of the Chandalar mining property: Unpublished report prepared for Goldrich Mining Company, 165 p. (on the Internet at http://www.goldrichmining.com/Files/chandalar/Chandalar_tech_rept_4_15_09.pdf, as of February 14, 2010).
Bundtzen, T.K., and Laird, G.M., 2007, Geologic map of the Chandalar Mining District, Brooks Range, Northern Alaska, 2007: Unpublished map prepared for Little Squaw Gold Mining Company, 1 sheet, scale 1:20,000. (on the Internet at http://www.goldrichmining.com/Files/chandalar/regional_chandalar_geo_map_final_07.pdf, as of February 14, 2010).
Buzzell, R.G., 2007, History of the Caro-Coldfoot trail (RST 262) and the Coldfoot-Chandalar trail (RST 9): Alaska Office of History and Archaeology, Report 17, 138 p.
Goldrich Mining Company, 2011, Goldrich completes Chandalar, Alaska Phase I exploration drilling: http://www.goldrichmining.com/news/45-goldrich-completes-chandalar-alaska-phase-i-exploration-drilling.html (News release, November 30, 2011).
Goldrich Mining Company, 2012, Chandalar gold district: http://www.goldrichmining.com/properties/chandalar-gold-district.html (of of March 25, 2012).
Heiner, L.E., and Wolff, E.N., eds., 1968, Mineral resources of northern Alaska, Final report, submitted to the NORTH Commission: University of Alaska, Mineral Industry Research Laboratory Report No. 16, 306 p.
Reporters J.M. Britton (Anchorage, Alaska); Travis Hudson (Applied Geology, Inc.); D.J. Grybeck (Contractor, USGS)
Last report date 4/1/2012