Democrat

Mine, Active

Alternative names

John Mitchell Lode
Camp Pit
Richardson project

Commodities and mineralogy

Main commodities Ag; As; Au; Sb
Other commodities Cu; Bi; Hg; Mo; Pb; U; Zn
Ore minerals acanthite; boulangerite; enargite; freibergite; gold; owyheeite; pyrargyrite; stephanite; stibnite; stetefeldtite; tetrahedrite
Gangue minerals ankerite; carbonate; quartz

Geographic location

Quadrangle map, 1:250,000-scale BD
Quadrangle map, 1:63,360-scale B-5
Latitude 64.3341
Longitude -146.3553
Nearby scientific data Find additional scientific data near this location
Location and accuracy The Democrat Mine is located at the head of Banner Creek (BD001), which has been placer mined for several miles below the Democrat Mine. The mine is centered about 3.5 miles north of the town of Richardson and about 0.5 mile east-southeast of the center of section 4, T. 7 S., R. 7 E., of the Fairbanks Meridian. Several unimproved roads provide access to the mine. It consists of a open cut in the hillside along Banner Creek. Some contiguous workings that are usually described with the Democrat Mine are sometimes called the Camp Pit. The location is accurate.

Geologic setting

Geologic description

The Richardson District is characterized by gentle slopes and broad, alluvium-filled valleys (Prindle and Katz, 1913). The area is unglaciated and largely overlain by windblown silt, sand, and loess, locally up to 50 meters thick (Foster and others, 1979). The rocks consist of three structure-bounded units (Weber and others, 1978; Swainbank and others, 1984; Noyes and others, 2006; Freeman, 2011). There is a core that consists mainly of biotite-hornblende-feldspar-quartz gneiss and lesser amphibolite, quartzite, marble and calc-silicate hornfels. The core is bounded on the north and south by amphibolite-grade pelitic schist. The contacts between the units are probably low-angle faults; north-trending vertical faults occur widely. Weber and others (1978) assign the pre-metamorphic age of the rocks to the Precambrian or Paleozoic. They were metamorphosed in the Middle to Late Devonian and recrystallized in the Early Cretaceous (Dusel-Bacon and others, 2004; Freeman, 2011). The metamorphic rocks are intruded by 90 Ma felsic to intermediate dikes and plugs, notably the quartz-feldspar porphyry at this site.
The Democrat Mine has been the focus of most of the recent work in the Richardson district (Freeman, 2011). The Democrat Mine was the first lode prospect discovered in the Richardson district in 1913. By 1921, three short adits, and two shafts had been driven on the property and a small arastra mill produced an unknown but probably small amount of gold (Brooks, 1923). Modern work in the area was initiated by Bundtzen and Reger (1977), and Swainbank and others (1984), who identified several areas of mineral potential and defined the general geology and geochemistry of the district. The first detailed work on the Democrat Mine was by John Mitchell in the late 1980s, and in 1987, the Tri-Valley Corporation (now Select Resources Corporation, Inc.) acquired the property and have retained it through the end of 2011.
Tri-Valley drilled one reverse circulation hole 101.5 feet deep in 1987 and collected many rock samples from the quartz-feldspar porphyry dike that hosts the mineralization; the hole averaged 0.013 ounce of gold per ton. In 1988, Tri-Valley and Asarco Inc. in a joint venture drilled 17 diamond drill holes that totaled 4,462 feet. The drilling was at 8 locations along about 3,400 feet of the quartz-feldspar porphyry dike. Some notable intercepts were 85 feet that averaged 0.032 ounce of gold per ton, 130 feet that averaged 0.185 ounce of gold per ton, and 175 feet that averaged 0.032 ounce of gold per ton. The highest grades were near the surface. Many (most?) of the investigators who subsequently reviewed the drill data concluded that the gold values were underestimated. Asarco terminated their agreement in late 1988. Later in 1988 and in 1989, Tri-Valley collected several large bulk samples on the surface of the deposit to prove that the Asarco drilling had underestimated the grade of the deposit. As a result of one of these episodes of bulk sampling, Mitchell (1989) estimated that the zone from which a large bulk sample was taken contained 18,750 tons of material that averaged 0.439 ounce of gold per ton. From another bulk-sample, Stearns (1989) identified four areas within the quartz porphyry dike that was estimated to contain 250,000 tons of material that averaged 0.07 ounces of gold per ton, or about 17,500 ounces of gold. Some (Freeman, 2011) considered the bulk sampling to be flawed. The bulk-sampling at the Democrat Mine in the 1980s produced 2,357 ounces of gold, the only lode gold produced in the district.
In 1991, Tri-Valley began working with TSNIGRI (Research Center of the Institute for Geological Exploration of Base and Precious Metals), of the Russian Ministry of Geology, and carried out geologic mapping, geophysics, and geochemical surveys at and around the Democrat Mine; the work continued to 2001. In 1997, Tri-Valley drilled 7 reverse-circulation holes at the Democrat property, completed several ground-geophysical grids, dug at least one trench, and collected numerous rock samples. The drilling was in the same general area as the 1987 and 1988 drilling. A report by Bright (1998) using drilling, and 1997 channel sampling estimated that 4 blocks of material 80-feet thick contained 141,539 tons of material with an average grade of 0.106 ounce of gold per ton (15,074 ounces). Freeman (2011) reported that an area about 1,200 feet long, 300-600 feet wide, and 200 feet thick averaged 0.65 part per million gold. In 2005, Select Resources (a subsidiary of Tri-Valley) compiled the previous information, sampled soils, and drilled 8 holes that totaled 930 meters. In 2010, Select collected fifteen, 25-kilogram samples for analysis.
The gold mineralization at the Democrat Mine is concentrated in the Democrat dike, which is up to 600 feet thick in the mine area. The dike has intruded along a northwest-trending, steeply-northeast-dipping structure (Freeman, 2011). The hanging wall is paragneiss; the footwall is lower-greenschist-facies rocks. The gold mineralization does not extend into the wall rocks. Locally, the dike thickens at flexures and is disrupted by northeast trending faults. The mineralization commonly is in quartz veins but the ore minerals are also disseminated in the dike rock. Locally, the ore is very rich, with a diverse suite of minerals including acanthite, freibergite, pyrargyrite, stephanite, stetefeldite, and owyheeite, boulangerite, stibnite, and enargite (Bundtzen, 2004). A suite of rich samples contained up to 28.323 ounces of gold per ton, 2,450 parts per million (ppm) copper, 5,320 ppm arsenic, 10,200 ppm antimony, 15,600 ppm lead, 28.1 ppm mercury, 56 ppm molybdenum, 88 ppm uranium, and more than 1 percent zinc. There is some indication of supergene enrichment. Geochemically, the gold is closely associated with silver, arsenic, copper, molybdenum, tungsten, and tin (Freeman, 2011).
McCoy and others (1997) describe several stages of alteration at the Democrat Mine. An early stage of alteration consists of quartz-tourmaline-muscovite +/- biotite +/- K-spar +/- clinozoisite. The stage more commonly associated with gold is an assemblage of quartz-white mica +/- ankerite +/- carbonaceous material. Locally, the plagioclase and K-spar phenocrysts are weathered to montmorillonite and kaolinite, respectively (D.J. Szumigala, oral communication, 1998). Albite is present in veins with quartz (R.J. Newberry, oral communication, 1998). In addition, the surrounding gneiss displays evidence of hornfelsing (K. Ausburn, oral communication, 1998).
In a recent synthesis of the many years of work at the property, Freeman (2011) proposes that the Democrat Mine is part of a structurally controlled, pluton related, boron enriched, gold-silver-tin-polymetallic hydrothermal system. McCoy and others (1977) include the Democrat Mine in their comprehensive article on the plutonic-related gold deposits of Interior Alaska.
Geologic map unit (-146.357658072425, 64.3336915515109)
Mineral deposit model Intrusion-related gold deposit; part of a structurally controlled, boron-enriched, gold-silver-tin-polymetallic hydrothermal system.
Age of mineralization Most of the mineralization is about 90 Ma (as are many of the intrusion-related gold deposits in central Alaska).
Alteration of deposit McCoy and others (1997) describe several stages of alteration at the Democrat Lode. An early stage of alteration consists of quartz-tourmaline-muscovite +/- biotite +/- K-spar +/- clinozoisite. The stage more commonly associated with gold is an assemblage of quartz-white mica +/- ankerite +/- carbonaceous material. Locally, the plagioclase and K-spar phenocrysts are weathered to montmorillonite and kaolinite, respectively (D.J. Szumigala, oral communication, 1998). Albite is present in veins with quartz (R.J. Newberry, oral communication, 1998). In addition, the surrounding gneiss displays evidence of hornfelsing (K. Ausburn, oral communication, 1998).

Production and reserves

Workings or exploration
The Democrat Mine has been the focus of most of the recent work in the Richardson district (Freeman, 2011). The Democrat Mine was the first lode prospect discovered in the Richardson district in 1913. By 1921, three short adits, and two shafts had been driven on the property and a small arrastra mill produced an unknown but probably small amount of gold (Brooks, 1923). Modern work in the area was initiated by Bundtzen and Reger (1977), and Swainbank and others (1984), who identified several areas of mineral potential and defined the general geology and geochemistry of the district. The first detailed work on the Democrat Mine was by John Mitchell in the late 1980s, and in 1987, the Tri-Valley Corporation (now Select Resources Corporation, Inc.) acquired the property and have retained it through the end of 2011.
Tri-Valley drilled one reverse circulation hole 101.5 feet deep in 1987 and collected many rock samples from the quartz-feldspar porphyry dike that hosts the mineralization. In 1988, Tri-Valley and Asarco Inc. in a joint venture drilled 17 diamond drill holes that totaled 4,462 feet. The drilling was at 8 locations along about 3,400 feet of the quartz-feldspar porphyry dike. Asarco terminated their agreement in late 1988. Later in 1988 and in 1989, Tri-Valley collected several large bulk samples on the surface of the deposit to prove that the Asarco drilling had underestimated the grade of the deposit.
In 1991, Tri-Valley began working with TsNIGRI (Research Center of the Institute for Geological Exploration of Base and Precious Metals), of the Russian Ministry of Geology, and carried out geologic mapping, geophysics, and geochemical surveys at and around the Democrat Mine; the work continued to 2001. In 1997, Tri-Valley drilled 7 reverse-circulation holes at the Democrat property, completed several ground-geophysical grids, dug at least one trench, and collected numerous rock samples. The drilling was in the same general area as the 1987 and 1988 drilling. In 2010, Select collected fifteen, 25-kilogram samples for analysis.
In 2016, Northern Empire Resources Corp. conducted exploration on their Richardson property, which hosts multiple intrusion-related as well as low- and high-angle fault-hosted lode gold prospects with gold ± silver ± arsenic ± antimony ± bismuth geochemical signatures. The project area includes the historical Democrat lode gold mine. In 2016, Northern Empire Resources Corp. collected rock chip-channel samples at 1-m intervals across 130 meters of the exposed face at Democrat. One 32-meter-long sample returned 5.73 grams of gold per tonne and 29.8 grams of silver per tonne, including 6 meters of 18.33 grams of gold per tonne and 48.95 grams of silver per tonne. Another sample collected about 61 meters away returned 2.57 grams of gold per tonne and 39.3 grams of silver per tonne across 6 m. Northern Empire also collected 1,298 geochemical samples across the Richardson property and conducted trenching, prospecting, 277 line-km of ground-magnetic geophysical surveys, identified structures in airborne geophysics, re-logged historical core holes, and delineated future drill targets. Work to date has identified a 2,000-meter-long, north–northeast-trending, gold-in-soil anomaly with a coincident geophysical structural signature. Additionally, 2,000 meters of the geophysical signature is poorly covered by soil data. A second northwest-trending mineralized structure was identified, with coincident elevated gold-in-soils over a 1,000-m strike length, with an additional 1,000 meters remaining to be evaluated by geochemical sampling (Athey and Werdon, 2017).
Indication of production Yes; small
Reserve estimates Since 1988, there have been several attempts to estimate the gold resources of the Democrat Mine. However, different criteria have been used, there has been some uncertainty about the accuracy of the data, and the samples do not necessarily overlap geographically. Mitchell (1989) estimated that a zone from which a large bulk sample was taken contained 18,750 tons of material that averaged 0.439 ounce of gold per ton. In another bulk-sampling effort, Stearns (1989) identified four areas in the quartz-feldspar porphyry dikes that were estimated to contain 250,000 tons of material that averaged 0.07 ounce of gold per ton, or about 17,500 ounces of gold. Based mainly on drilling and surface sampling to 1998, Bright (1998) estimated that 4 blocks of material 80-feet thick contained 141,539 tons of material with an average grade of 0.106 ounce of gold per ton (15,074 ounces). Freeman (2011) estimated that an area about 1,200 feet long, 300-600 feet wide, and 200 feet thick averaged 0.65 part per million gold.
Production notes There probably was a small but undocumented amount of gold produced from 1913 to 1922 from a small arrastra mill. The only other production was 2,357 ounces of gold that was recovered in 1988 and 1989 during the processing of several large bulk samples collected at the surface.

Additional comments

In his synthesis of more than 25 years of the work on the Democrat Mine and the surrounding area, Freeman (2011) lists and cites data that he had access to from a voluminous body of unpublished, internal reports done for the Tri-Valley Corporation and other companies. Some of Freeman's references not included in the reference list that follows may only peripherally relate to this deposit and most are not available publicly.
This site is part of the Richardson project (as of 2016).

References

MRDS Number A012486

References

Bundtzen, T.K., 2004, Compilation of past geological investigations and 2004 sampling program and analytical results from Tri-Valley Corporation properties in the Richardson mining District, eastern Interior Alaska: Internal Report. Prepared for Tri-Valley Crop. by Pacific Rim Geological Consulting Inc., 71 p.
Ebert, S.; Dilworth, K.; Roberts, P; Smith, M and Bressler, J, 2003, Quartz veins and gold prospects in the Goodpaster Mining district in Ebert, S. [ed], 2003, Regional geologic framework and deposit specific exploration models for Intrusion-related gold mineralization, Yukon and Alaska: Mineral Deposits Research Unit, Spec. Pub. 3, p. 256-281.
Flanigan, B., Freeman, C., Newberry, R., McCoy, D., and Hart, C., 2000, Exploration models for mid and Late Cretaceous intrusion-related gold deposits in Alaska and the Yukon Territory, Canada, in Cluer, J.K., Price, J.G., Struhsacker, E.M., Hardyman, R.F., and Morris, C.L., eds., Geology and Ore Deposits 2000: The Great Basin and Beyond: Geological Society of Nevada Symposium Proceedings, May 15-18, 2000, pp. 591-614.
McCoy, Dan, Newberry, R.J., Layer, Paul, DiMarchi, J.J., Bakke, Arne, Masterman, J.S., and Minehane, D.L., 1997, Plutonic-related gold deposits of interior Alaska: in Economic Geology Monograph 9, p. 191-241.
Mitchell, J.R., 1989, Exploration update, Richardson prospect, Alaska: Internal report prepared for Tri-Valley Corporation, 22 p.
Reporters Cameron S. Rombach (ADGGS); D.J. Grybeck (Contractor, USGS); M.B. Werdon (DGGS)
Last report date 8/26/2017