|Quadrangle map, 1:250,000-scale||FB|
|Quadrangle map, 1:63,360-scale||D-2|
|Nearby scientific data||Find additional scientific data near this location|
|Location and accuracy||The Scrafford mine is located in the SE1/4 sec. 16, T. 2 N., R. 1 W., Fairbanks Meridian. This mine is accessible from the Elliott Highway and Old Murphy Dome Road. Approximately 4 miles down Old Murphy Dome Road, a steep, rough road leads 0.5 mile north to the Scrafford mine. The mine is just north of the southeast fork of Eagle Creek, a tributary of Treasure Creek.|
The Scrafford mine is the largest producer of antimony ore in the Fairbanks mining district; production has been estimated at more than 2,700 tons of ore (Robinson and Bundtzen, 1982). Mining from open cuts took place from 1915 to 1916, in 1926, and from 1968 to 1970 (Cobb, 1976 [OFR 76-662, p. 169-170]). The deposit consists of massive stibnite localized along shear zones associated with stockwork-type quartz veinlets containing disseminated arsenopyrite and stibnite. The stibnite occurs in fibrous and columnar twinned crystals and as fine-grained massive aggregates (Robinson and Bundtzen, 1982). In 1916, an assay of mineralized rock showed an average grade of $4 in gold (about 0.19 ounce of gold per ton) and 8 ounces of silver per ton (Brooks, 1916 [B 649, p. 29]). Most of the antimony ore that was produced had grades of 56 to 60 percent antimony; ore mined in 1970 and 1971 had a lower grade of 12 to 16 percent antimony (Robinson and Bundtzen, 1982, p. 3).
In 1982, Robinson and Bundtzen (1982) spent three days mapping and sampling several trenches on the Scrafford property and the following is a summary of their findings. Rocks in the trenches include quartz-mica schist, micaceous quartz schist, calc-schist, feldspathic schist, felsic tuff, and graphitic schist. Several felsic dikes are also present. The center of antimony-gold mineralization occurs along an east-west-trending shear zone that separates a barren hanging-wall sequence of quartz-muscovite schist, micaceous quartzite, and quartz-feldspar schist from a mineralized footwall sequence of feldspathic, micaceous quartzite and minor quartz-mica schist. The footwall rocks are highly oxidized, sheared, and cut by anastomosing quartz-sulfide veinlets. The shear zone in the main open cut is exposed for at least 320 feet; it strikes N. 80-85 E and dips 55-60 S. The stibnite-bearing vein in the shear pinches and swells from a width of 4 to 19 feet and is confined to the footwall side of the shear zone. The shear zone ranges from 6 to 38 feet wide. The hanging wall of the shear zone is dominated by incompetent quartz-mica schist, and the footwall is locally mineralized feldspathic quartzite (metatuff). The footwall quartzite is competent and highly fractured; the result is a favorable site for ore deposition.In 1991-93, American Copper and Nickel Company drilled three reverse-circulation holes to investigate gold mineralization within the shear zone and in the silicified footwall schist (Dashevsky, 1993). The 1992 core hole was 330 feet deep. Nineteen feet assayed 0.107 ounce of gold per ton; five feet in the Scrafford shear zone assayed 0.026 ounce of gold per ton; and 14 feet in the silicified footwall assayed 0.136 ounce of gold per ton. The drilling program indicated that the footwall mineralization is confined within a narrow, sub-parallel zone beneath the Scrafford shear, and was probably not a viable bulk-minable target (Dashevsky, 1993).
|Geologic map unit||(-147.759441925458, 64.9985690350131)|
|Mineral deposit model||Simple Sb deposit (Cox and Singer, 1986; model 27d)|
|Mineral deposit model number||27d|
|Alteration of deposit||The footwall rocks of the deposit are highly oxidized and contain stibiconite and scorodite (Robinson and Bundtzen, 1982, p. 5). The main shear is filled with black graphitic gouge, bright-orange iron-stained clay, and white clay that supports clasts of schist, stibnite, and stibnite oxidation products (Dashevsky, 1993). Strong clay and sericite alteration is confined to gouge zones within the shear. The schist footwall is silicified and quartz veined (Dashevsky, 1993).|
|Workings or exploration||
Mining from open cuts took place from 1915 to 1916, in 1926, and from 1968 to 1970 (Cobb, 1976 [OFR 76-662, p. 169-170]). The shear-zone system in the main opencut is exposed for at least 320 feet (Robinson and Bundtzen, 1982). In 1982, Robinson and Bundtzen (1982) spent 3 days mapping and sampling several trenches on the Scrafford property. In 1991-93, American Copper and Nickel Company conducted soil sampling and drilled three reverse-circulation holes, totalling 1295 feet, to pursue the gold potential that was reported by Robinson and Bundtzen (Dashevsky, 1993).In 2016, the Treasure Creek Partnership consolidated three, separately owned properties, including numerous prospects and occurrences (LG038; LG039; FB074; FB075; FB076; FB077; FB078; FB079; FB080; FB081) in the Treasure and Any Creek watersheds that potentially host plutonic-related, lode-gold mineralization contained in shear zones north of Fairbanks. Exploration activity in 2016 included conducting field work and reviewing and updating 1990s-era exploration information (Athey and Werdon, 2017).
|Indication of production||Yes; small|
|Production notes||Mining from open cuts took place from 1915 to 1916, in 1926, and from 1968 to 1970 (Cobb, 1976 [OFR 76-662, p. 169-170]). Production has been estimated at over 2,700 tons of ore, much of it from ore that ran 50 to 60 percent antimony (Robinson and Bundtzen, 1982).|
Chapin, Theodore, 1914, Placer mining in the Yukon-Tanana region: U.S. Geological Survey Bulletin 592-J, p. 357-362.
Chapin, Theodore, 1919, Mining in the Fairbanks district: U.S. Geological Survey Bulletin 692-F, p. 321-327.
Dashevsky, S.S., 1993, Eagle Creek project (Au), Fairbanks district, Alaska: American Copper and Nickel Company, Inc., 60 p. (Report held by Sam Dashevsky, Northern Associates Inc., Fairbanks, Alaska; can be examined with permission from current lease holders).
Hill, J.M., 1933, Lode deposits of the Fairbanks district, Alaska: U.S. Geological Survey Bulletin 849-B, p. 29-163.
Killeen, P.L., and Mertie, J.B., 1951, Antimony ore in the Fairbanks District, Alaska: U.S. Geological Survey Open-File Report 51-46, 43 p.
|Reporters||J.R. Guidetti Schaefer and C.J. Freeman (Avalon Development Corporation); M.B. Werdon (DGGS)|
|Last report date||8/26/2017|