Wyoming

Mine, Active

Commodities and mineralogy

Main commodities Ag; Au
Other commodities As; Pb; Sb; W; Zn
Ore minerals arsenopyrite; boulangerite; jamesonite; gold; scheelite; stibnite
Gangue minerals calcite; quartz

Geographic location

Quadrangle map, 1:250,000-scale LG
Quadrangle map, 1:63,360-scale A-1
Latitude 65.0635
Longitude -147.4376
Nearby scientific data Find additional scientific data near this location
Location and accuracy The Wyoming Mine is about 400 yards south of the Cleary Hill Mine (ARDF no. LG119) on the east side of Bedrock Creek. It is in the NW1/4NW1/4 section 31, T. 3 N., R. 2 E., of the Fairbanks Meridian.

Geologic setting

Geologic description

Note: As of 2008, this site and several others in the vicinity are being explored as a single entity by Freegold Ventures Inc. (Freeman, 2008) Considerable new mineralization has been discovered that indicates this is part of a larger mineralized system that is described as a separate ARDF site (LG205).
The Wyoming Mine is along a shear zone with quartz veins up to 2 feet thick that contain gold, stibnite and scheelite. Scheelite was particularly abundant in the wall rocks and along the margins of the shear zone (Moffit, 1927). The shear zone strikes N 80 E and dips 50 S (Hill, 1933). Ore in the main stope averaged about $6.00 of gold per ton (0.3 ounces of gold per ton) and consisted of 12 to 14 inches of hard white quartz and brecciated schist with minor iron-oxide staining (Hill, 1933).
The Wyoming prospect was investigated in 1943 as a possible source of tungsten (Byers, 1957). Scheelite is present in limestone lenses found east of the north-trending fault in both the Wyoming and Lower adits. By 1943, the Wyoming adit consisted of 350 feet of drift west of the north-trending fault, a 100-foot crosscut to the south on the east side of the north-south fault, and 200 feet of drift along the Wyoming shear zone from the end of the 100-foot crosscut (Byers, 1957). A 70-foot section of the 200-foot drift east of the fault averaged 0.3 percent tungsten oxide over 6 inches. In a sublevel stope above the same zone, a 1-foot by 3-foot area averaged 20 percent tungsten oxide in a limestone replacement body (Byers, 1957). Samples found on the Lower adit dump, and samples collected in place from the Wyoming shear zone in the Lower adit contained 0.28 to 1.64 percent tungsten oxide with trace molybdenum, manganese, antimony and arsenic.
Fairbanks Exploration Inc. conducted 11 man-days of field work on the Wyoming prospect in 1987. Nineteen rock samples were collected and the alteration zones were mapped. Several samples were collected from bedrock exposures and dumps in and around the mine (Fairbanks Exploration Inc., unpublished report, 1987). These samples contained low gold, antimony, and silver, and elevated arsenic. Gold values were higher where jamesonite and/or boulangerite are visible in the shear zone. Most of the dump material on the Wyoming dump is sulfide-free, white quartz, attesting to close grade control during mining. Stratiform arsenopyrite lenses up to 4 inches thick were discovered on bedrock exposures in a placer cut below the dump of the Lower adit. These occurrences are associated with rhyolitic tuff beds; samples had unexpectedly low gold values (Fairbanks Exploration Inc., unpublished report, 1987).
In 1989, Fairbanks Exploration Inc. conducted 10 man-days of field work on the prospect and collected eighteen rock samples (Fairbanks Exploration Inc., unpublished report, 1989). Exposures in the old placer cut on lower Bedrock Creek consist of pale-yellow to gray, thinly bedded, felsic volcanic tuff and siliceous exhalite containing quartz, sericite, minor chlorite, and disseminated pyrite and lesser arsenopyrite. These units are correlative with the upper third of the Cleary Sequence. Foliation in this area trends N60-80E and dips 10 to 20SE. The rocks are heavily jointed and appear to have undergone minor dip-slip deformation along sericite-rich bedding planes. Sulfide mineralization is concentrated along stratiform horizons which vary from one inch to over six inches in thickness. Visible gold was found in one of these horizons early in 1989 after heavy rains exposed new outcrops in this area. The sulfide contents of the exhalite are from 5 to 25 percent of the rock; the ground mass consists of fine-grained quartz, and clay after feldspar.
Sample results from the 1989 program indicate that highly anomalous gold and arsenic, and weakly anomalous antimony, lead and zinc are associated with felsic tuff and exhalite over the entire area exposed along the creek bottom and the banks of lower Bedrock Creek (Fairbanks Exploration Inc., unpublished report, 1989).
Geologic map unit (-147.440047699203, 65.0630767888917)
Mineral deposit model Gold-quartz vein.
Age of mineralization Probably about 90 Ma based on analogy with similar gold deposits nearby.
Alteration of deposit The rocks in the old placer cut on lower Bedrock Creek are heavily jointed and appear to have undergone minor dip-slip deformation along sericite rich bedding planes.

Production and reserves

Workings or exploration
By 1909, development work had begun on the Wyoming shear zone (Prindle, 1910). By the end of 1910, 300 feet of adit had been driven on the Wyoming shear and 50 feet of shaft had been sunk on the Carlisle Fraction claim which was adjacent to the Cleary Hill mine (Brooks, 1911). At the 80-foot station of the Wyoming adit, a 50-foot winze was sunk at an angle of 60 degrees south, but was flattened to 49 degrees south near the bottom of the winze (Smith, 1913b). An unknown amount of material from the winze was custom milled and reportedly returned high values in gold.
In 1913, the Wyoming prospect. was being mined at the surface. Four tons of ore were custom milled at the Blue Moon Mazeppa Mine on Chatham Creek and another 4.5 tons was stockpiled (Chapin, 1914). No production records are available for these two shipments. Limited development was carried out at the Wyoming prospect in 1914. In 1915, development activities continued on the Wyoming shear and were expanded to the Colorado shear located about 500 feet north of and parallel to the Wyoming shear (Stewart, 1915). Thirty-nine tons of ore from these two shear zones were custom milled at the Blue Moon Mazeppa mill on Chatham Creek but no production figures are available. Development of the Wyoming prospect was discontinued by 1916 (Brooks, 1918), but limited mining was conducted on the prospect in 1917 (Martin, 1919).
Development work on the Wyoming adit began again in 1921 when the adit was lengthened and a 60-foot winze sunk from the adit level (Brooks, 1921). The Wyoming shear was traced onto the adjacent Alabama claim in 1922 (Davis, 1922; Stewart, 1922). By 1923, the Wackwitz brothers erected a small, ball mill and mined a limited amount of high grade ore from the Wyoming adit. The ore averaged averaged $10-20 of gold per ton (0.5 to 1.0 ounce of gold per ton) with recovery estimated at 85 percent (Loftus, 1927). The prospect was operated by the Gustafson brothers in 1924 and produced a small amount of gold (Smith, 1926). A new ball mill was installed in 1925 and operated for one month.
By 1927, the Wyoming shear was accessible through three adits, the Lower, Wyoming (upper) and Crawford adits; these totaled 500 feet of workings over 150 vertical feet of shear zone (Loftus, 1927). Production continued in 1927, and ore was milled at the nearby Cleary Hill mill (Smith, 1930). Development work increased and surface facilities were improved in 1928 (Smith, 1930). Minor production from the prospect continued in 1929 and 1930 (Smith, 1932; Smith, 1933). By 1930, developments at the Wyoming mine consisted of the 165- foot- long Wyoming adit and a Lower adit 1,000 feet long, approximately 100 feet lower than the Wyoming adit (Pilgrim, 1931; Stewart, 1931). The Crawford adit was 75 feet long and approximately 40 feet above the Wyoming adit. By 1931, a fourth adit had been driven 60 feet on a sheared gold-quartz parallel to the Wyoming shear zone (Pilgrim, 1931; Stewart, 1933).
In 1931, the Wyoming adit was caved and inaccessible. The Lower adit followed the Wyoming shear zone for 300 feet where the shear was faulted about 100 feet to the south (Hill, 1933). A raise connected the Lower and Wyoming adits. A stope that extended for about 70 feet along strike connected the Lower adit to the Wyoming adit and appears to rake about 45 degrees to the west (Hill, 1933). Development work in the Crawford adit followed a north-dipping shear zone which is separate from the Wyoming shear.
Reed (1939) reported that in 1938 Fred and Ernest Wackwitz completed 30 feet of drifting, 20 feet of crosscuts, 125 feet of adit, and milled 56 tons of ore with an average grade of $47 of gold per ton (1.34 ounces of gold per ton). The ore was milled on site in a 20-ton Herman ball mill. By 1943, the Wyoming adit consisted of 350 feet of drift west of the north-south fault, a 100 foot crosscut to the south on the east side of the north-trending fault, and 200 feet of drift along the Wyoming shear from the end of the 100-foot crosscut (Byers, 1957).
In 1987, Fairbanks Exploration Inc. conducted eleven man-days of field work on the Wyoming prospect. Nineteen rock samples were collected and an alteration map prepared. Several samples were collected from bedrock exposures and dumps in and around the Wyoming mine site (Fairbanks Exploration Inc., unpublished report, 1987). In 1989, Fairbanks Exploration Inc. conducted ten man-days of field work on the prospect and collected eighteen rock samples (Fairbanks Exploration Inc., unpublished report, 1989). The alteration in the old placer cut on lower Bedrock Creek was also studied and mapped.
Indication of production Yes; small
Production notes
Smith (1913b) reported that an unknown amount of ore was custom milled in 1913 from the Wyoming adit. In 1913, the Wyoming was mined at the surface. In 1913, four tons of ore were custom milled at the Blue Moon Mazeppa mine on Chatham Creek and another 4.5 tons was stockpiled (Chapin, 1914). In 1915, thirty-nine tons of ore were custom milled at the Blue Moon Mazeppa mill on Chatham Creek but no production figures are available.
By 1923, the Wackwitz brothers erected a small, ball mill and mined a limited amount of high grade ore from the Wyoming adit. Ore grades averaged $10-20 of gold per ton (0.5 to 1.0 ounces of gold per ton) with recovery estimated at 85 percent (Loftus, 1927). Production continued in 1927, and ore was milled at the nearby Cleary Hill mill (Smith, 1930). Minor production from the prospect continued in 1929 and 1930 (Smith, 1932; Smith, 1933). Reed (1939) reported that 56 tons of ore were milled with an average grade of $47 of gold per ton (1.34 ounces of gold per ton).

References

MRDS Number A015432; D002660

References

Freeman, C.J., 1992, 1991 Golden Summit project final report, volume 2: Historical summary of lode mines and prospects in the Golden Summit project area, Alaska: Avalon Development Corp., 159 p. (Report held by Freegold Recovery Inc. USA, Vancouver, British Columbia.)
Freeman, C.J., 2008, Executive summary report for the Golden Summit project, Fairbanks Mining District, Alaska: Unpublished Technical Report for Freegold Ventures Ltd., 112 p. (posted on www.sedar.com, March 31, 2008).
Smith, S.S., 1917, The mining industry in the territory of Alaska during the calendar year 1915: U.S. Bureau of Mines Bulletin 142, 66 p.
Reporters C.J. Freeman, J.R. Guidetti Schaefer (Avalon Development Corporation); D.J. Grybeck (Port Ludlow, WA)
Last report date 6/5/2008