Portage Creek

Mine, Active

Commodities and mineralogy

Main commodities Au
Other commodities Bi; Cu; Sn; U; W; Zn

Geographic location

Quadrangle map, 1:250,000-scale CI
Quadrangle map, 1:63,360-scale B-2
Latitude 65.462
Longitude -144.613
Nearby scientific data Find additional scientific data near this location
Location and accuracy The placered area extends about 3/4 mile up and downstream from the intersection of the coordinates. Portage Creek flows in a northeasterly direction and can be accessed by gravel road just a few miles east of Circle Hot Springs.

Geologic setting

Geologic description

Portage Creek near its source is underlain by Cretaceous granite, then flows over chlorite-muscovite schist and Tertiary granite before crossing into the Tintina fault zone. Almost all of the mining has been conducted south (upstream) of the Tintina fault zone. Gold is restricted to the upper 0.5 meters of the orange, schist-rich gravel.
A high percentage of the detritus in Portage Creek is colluvium, so the mined gravel is poorly sorted (Yeend, 1991). One meter of muck typically overlies 2 meters of colluvial-alluvial gravel. A defined 'pay streak' is not often present due to the colluvial mixing and lack of alluvial water to wash and sort. Because of the thick colluvial gravel cover on the side slopes, the mined gravel channel is quite narrow, only 20 to 30 meters (Yeend, 1991). Placer concentrates contain allanite, arsenopyrite, bismuthinite, cassiterite, garnet, gold, hematite, ilmenite, magnetite, monazite, pyrite, scheelite, sphalerite, sphene, spinel, topaz, tourmaline, uranothorianite, wolframite and zircon (Nelson and others, 1954).
Gold was not discovered on the creek until the early 1900s (Brooks, 1907). Full-scale mining did not begin on the creek until 1933. Two miners worked the upper valley in 1936. One operation consisted of drift mining and one was a prospecting shaft (Mertie, 1938). Gravel valued at 0.025 to 0.0625 ounces per cubic yard was being mined in 1937 by several miners shoveling in an opencut (Lampright, 1996, p. 74). There were two operations on the creek in 1975 and anywhere from two to five operations per year during the 1980s (Yeend, 1991). Points North operation on Portage Creek was the biggest producer of gold in the Circle district in 1994 (Swainbank and others, 1994, p. 28).
Ten ounces of gold were reportedly recovered from one claim on the creek in 1906 (Brooks, 1907, p. 198) and various mines have been operating on and off to the present. Points North operation on Portage Creek was the biggest producer of gold in the Circle district in 1994 (Swainbank and others, 1994, p. 28).
Geologic map unit (-144.615447879255, 65.4616388014055)
Mineral deposit model Placer gold deposit (Cox and Singer, 1986; model 39a)
Mineral deposit model number 39a

Production and reserves

Workings or exploration Gold was not discovered on the creek until the early 1900s (Brooks, 1907). Full-scale mining did not begin on the creek until 1933. Two miners worked the upper valley in 1936. One operation consisted of drift mining and one was a prospecting shaft (Mertie, 1938). Gravel valued at 0.025 to 0.0625 ounces per cubic yard was being mined in 1937 by several miners shoveling in an opencut (Lampright, 1996, p. 74). There were two operations on the creek in 1975 and anywhere from two to five operations per year during the 1980s (Yeend, 1991). Points North operation on Portage Creek was the biggest producer of gold in the Circle district in 1994 (Swainbank and others, 1994, p. 28).
Indication of production Yes; medium
Production notes Ten ounces of gold were reportedly recovered from one claim on the creek in 1906 (Brooks, 1907, p. 198) and various mines have been operating on and off to the present. Points North operation on Portage Creek was the biggest producer of gold in the Circle district in 1994 (Swainbank and others, 1994, p. 28).

Additional comments

There are two different Portage Creeks in the Circle mining district, both of which flow away from the same divide. One creek flows south-southwest and has not yielded gold. The Portage Creek discussed for this site flows north-northeast into Medicine Lake.

References

MRDS Number A012236; D002687

References

Lampright, R.L., 1996, Gold placer deposits near Fairbanks Alaska--An inventory of the gold placer mines, prospects, and deposits located within the Big Delta Charley River, Circle, Eagle, Fairbanks, and Livengood quadrangles: Nederland, Colorado, Iron Fire Publications, Anchorage, Alaska, 135 p.
Reporters C.J. Freeman, J.R. Guidetti Schaefer, A.S. Clements (Avalon Development Corporation)
Last report date 9/9/1998