Sixmile Creek

Mine, Active

Commodities and mineralogy

Main commodities Au
Ore minerals gold

Geographic location

Quadrangle map, 1:250,000-scale SR
Quadrangle map, 1:63,360-scale D-7
Latitude 60.8786
Longitude -149.4297
Nearby scientific data Find additional scientific data near this location
Location and accuracy Sixmile Creek is located in T. 8 and 9 N., R. 1 W., of the Seward Meridian. It flows north from East Fork Sixmile Creek to Turnagain Arm, entering tidewater at the town of Sunrise. The map site representing this placer mine is in the SE1/4 section 10, T. 9 N., R. 1 W., of the Seward Meridian. This is location 141 of Cobb and Richter (1972), location 165, 166 and 215 of MacKevett and Holloway (1977), location 13 of Cobb and Tysdal (1980), and location P-72 of Jansons and others (1984). This location is accurate to 300 feet.

Geologic setting

Geologic description

Sixmile Creek flows in a broad, flat-bottomed valley in its upper half, cuts into Valdez Group bedrock of Late Cretaceous age for about 3 miles, and then broadens into a wider valley for about its final 3 miles (Tysdal, 1978 [MF-880-B]). Several bedrock canyons along its channel are separated by alluvial terraces and partially covered with avalanche debris (Jansons and others, 1984).
Jansons and others (1984) indicated that small, auriferous alluvial fan deposits are associated with several western tributaries to the lower reaches of Sixmile Creek. These include Alder Creek, Cub Creek, and Old Woman Creek. The flood-plain deposits near the junction of Sixmile Creek with Canyon Creek appear to be fairly thick, with depths to bedrock in excess of 70 feet (Jansons and others, 1984).
Geologic map unit (-149.431873166532, 60.8780461062102)
Mineral deposit model Placer Au (alluvial) (Cox and Singer, 1986; model 39a).
Mineral deposit model number 39a
Age of mineralization Quaternary.

Production and reserves

Workings or exploration
Sixmile Creek has produced only modest amounts of gold (Jansons and others, 1984). At the junction of this creek and Canyon Creek, an attempt was made to reach bedrock by means of a hydraulic elevator, but at the time Paige and Knopf (1907) visited in 1906, the work had ceased. Martin and others (1915) reported that placer mining on Sixmile Creek was confined to a very few small hydraulic plants, worked by individuals, operating on high bench gravels bordering the stream and yielding only a small production. Tuck (1933) reported that prospecting on the benches in the lower reaches had picked up several old pay channels. Tysdal (1978 [MF-880-B]) indicated that the stream gravels in the lowermost part of Sixmile Creek contain muds from Turnagain Arm and have yielded little gold. However, in the lower 3 miles of the creek, some gold has been recovered from high bench gravels containing several old channels.
According to Jansons and others (1984), the gravels just below Canyon Creek were tested by a backhoe and 12-inch suction dredge, but the results are unknown.
Overall, the gold is fairly fine, and nuggets larger than one-quarter inch are rarely recovered (Jansons and others, 1984).
In the early 1980s, the U.S. Bureau of Mines collected a 0.1 cubic yard sample that contained 0.0017 ounce of gold per cubic yard. One suction dredge sample from the active stream channel of Cub Creek contained 0.0073 ounce gold per cubic yard. Two section dredge samples collected from channel deposits of Sixmile Creek yielded 0.002 and 0.0182 ounce of gold per hour, and one bedrock pan sample contained 0.0214 ounce of gold per cubic yard (Jansons and others, 1984).
Indication of production Yes; small
Reserve estimates The volume of bench and channel deposits is estimated to exceed 5 million cubic yards. There are no estimates of grade or total gold content (Jansons and others, 1984).
Production notes The total estimated production is 1,500 to 2,000 ounces of gold, of which less than 250 ounces has been produced since 1975 (Jansons and others, 1984).

References

MRDS Number A010627

References

Hoekzema, R.P., and Sherman, G.E., 1983, Mineral investigations in the Chugach National Forest, Alaska (Peninsula study area): U.S. Bureau of Mines in-house report; held at U.S. Bureau of Land Management Alaska State Office, Anchorage, 524 p.
Smith, S.S., 1917, The mining industry in the Territory of Alaska during the calendar year 1915: U.S. Bureau of Mines Bulletin 142, 65 p.
Smith, S.S., 1917, The mining industry in the Territory of Alaska during the calendar year 1916: U.S. Bureau of Mines Bulletin 153, 89 p.
Reporters Jeff A. Huber (Anchorage)
Last report date 5/14/2000