Franklin Creek

Mine, Inactive

Alternative names

Franklin Gulch

Commodities and mineralogy

Main commodities Au
Other commodities Ag; Hg; Pb
Ore minerals barite; cinnabar; galena; gold; magnetite; native lead; native silver; pyrite

Geographic location

Quadrangle map, 1:250,000-scale EA
Quadrangle map, 1:63,360-scale A-2
Latitude 64.1642
Longitude -141.7811
Nearby scientific data Find additional scientific data near this location
Location and accuracy Franklin Creek drains eastward into the South Fork of the Fortymile River. The mine coordinates are the small abandoned town of Franklin shown on the U.S. Geological Survey 1:63,360-scale topographic map of the Eagle A-2 quadrangle (1956; revised in 1971), in section 36, T. 28 N., R. 18 E., of the Copper River Meridian. The location is accurate. Placer mining occurred along the lower 4 miles of the creek. This site is locality 70 of Burleigh and Lear (1994), locality 30 of Eberlein and others (1977), and locality 55 of Cobb (1972 [MF-393]).

Geologic setting

Geologic description

The rocks in the vicinity of Franklin Creek consist predominantly of Paleozoic amphibolite-facies paragneiss, quartzite, schist, hornblende-plagioclase gneiss, and marble (Werdon and others, 2001). These units are cut by a high-angle, east-west-trending fault that follows the upper portion of the Franklin Creek. South of the fault, the metamorphic rocks are intruded by the Chicken pluton, which has a hornblende 40Ar/39Ar plateau age of 187.8 +/- 0.9 Ma (Layer and others, 2002). The metamorphic rocks are also cut by widespread granite-pegmatite and clinopyroxenite dikes that are mineralogically and compositionally similar to Jurassic intrusions dated elsewhere in the area. Quaternary colluvium deposits are extensive in the upper part of the Franklin Creek.
All of the placer mining activity on Franklin Creek took place within 4 miles of its mouth; the valley here is narrow and the gravel is thinner than farther upstream. Gold was also found in prospecting pits in the upper part of the valley. Gravel in lower Franklin Creek is approximately 2 to 12 feet thick. Placer gold was mainly found on and within the top 2 feet of fractured bedrock and, to a lesser extent, within the lower 2 feet of the gravel (Mertie, 1930 [B 813-C]; Mertie, 1938). The pay streak was about 50 feet wide. The gold is coarse and angular, and some nuggets have quartz attached to them. Small nuggets are common, and nuggets as large as 30 ounces were found in the early days near the mouth of the creek (Spurr, 1898). Mertie (1938) estimated a gold fineness of 820 parts of gold per thousand from the price per ounce reported by Spurr (1898); Smith (1941 [B 910-C]) reported a single value of 817 parts gold per thousand from Franklin Creek. Placer concentrates contain magnetite, garnet, ilmenite, limonite, barite, cinnabar, gold, and a trace of galena and pyrite (Mertie, 1930 [B 813-C]). In addition, native lead was observed by Prindle (1908 [B 345]).
Placer gold was first discovered in 1886 on Franklin Creek; according to Spurr (1898) and Smith (1968), it is the site of the first placer gold mine within the United States part of the Fortymile mining district. Yeend (1996) states that Howard Franklin found gold on Franklin Creek largely because he believed the gold at Troublesome Point just downstream on the Fortymile River was coming from the first creek above it (Buteau, 1967). Franklin Creek was mined almost continuously between 1886(?) and 1935 by drift and open cut methods. The placer deposits were nearly exhausted by 1935 (Powers, 1935). In 1935 a disastrous flood wiped out dams and filled all of the placer cuts with gravel (Mertie, 1938).
Gold was produced prior to 1899 (Brooks, 1900). Some of the ground prior to 1905 ran as high as $5 per square yard of bedrock (gold at $20.67 per ounce), but the average was lower (Prindle, 1905). Production between 1904 and 1907 was about 1,960 fine ounces of gold (Prindle, 1908). Mining during the winter of 1908-1909 and the summer of 1909 yielded $10,000 worth of gold (at $20.67 per ounce) (Ellsworth, 1910).
Geologic map unit (-141.783388496448, 64.1638722518709)
Mineral deposit model Placer Au (Cox and Singer, 1986; model 39a).
Mineral deposit model number 39a
Age of mineralization Quaternary.

Production and reserves

Workings or exploration The creek was mined almost continuously between 1886(?) and 1935 by drift and open cut methods. The placer deposits were nearly exhausted by 1935 (Powers, 1935). In 1935 a disastrous flood wiped out dams and filled all of the placer cuts with gravel (Mertie, 1938). All of the placer mining activity took place within 4 miles of its mouth; the valley here is narrow and the gravel is thinner than farther upstream. Gold was also found in prospecting pits in the upper part of the valley.
Indication of production Yes; small
Production notes Gold was produced prior to 1899 (Brooks, 1900). Some of the ground prior to 1905 ran as high as $5 per square yard of bedrock (gold at $20.67 per ounce), but the average was lower (Prindle, 1905). Production between 1904 and 1907 was about 1,960 fine ounces of gold (Prindle, 1908). Mining during the winter of 1908/1909 and the summer of 1909 yielded $10,000 worth of gold (at $20.67 per ounce) (Ellsworth, 1910).

References

MRDS Number A015160

References

Brooks, A.H., 1900, A reconnaissance from Pyramid Harbor to Eagle City, Alaska, including a description of the copper deposits of the upper White and Tanana Rivers: U.S. Geological Survey Twenty-first Annual Report, p. 331-391, plate 2.
Buteau, Frank, 1967, My experiences in the world: in Heller, H.L., ed., Sourdough Sagas: Cleveland, Ohio, The World Publishing Company, p. 93-118.
Layer, P.W., Drake, J., and Szumigala, D.J., 2002, 40Ar/39Ar dates for mineralization and igneous and metamorphic rocks in a portion of the Fortymile mining district, Eagle quadrangle, Alaska: Alaska Division of Geological and Geophysical Surveys Preliminary Interpretive Report. [In preparation in 2002]
Malone, Kevin, 1965, Mercury in Alaska, in Mercury potential of the United States: U.S. Bureau of Mines Information Circular 8252, p. 31-59.
Reporters M.B. Werdon
Last report date 5/1/2002