Mulchatna

Occurrence, Undetermined

Commodities and mineralogy

Main commodities Au
Ore minerals gold

Geographic location

Quadrangle map, 1:250,000-scale LC
Quadrangle map, 1:63,360-scale B-8
Latitude 60.471
Longitude -155.693
Nearby scientific data Find additional scientific data near this location
Location and accuracy About 13 km northeast of VABM Overlook, near where the southeast flowing Springway Creek enters the Mulchatna River. NW1/4 sec. 3, T. 4 N., R. 37 W., of the Seward Meridian. Locality is accurate to within 800 m.

Geologic setting

Geologic description

Spurr (1900) reported placer gold, too flaky and fine to save, 200 miles from mouth of river as early as 1890. Brooks (1904) reported gold has long been known in the upper reaches of the river. Placer said to yield $4-5 per day per man in 1903, but area too remote for mining. Cobb (1976) indicated he thought Brooks (in 1904 report) may have been discussing placers of Bonanza Creek.
The most abundant bedrock in the areas upstream of the claims is unit KJs (Nelson and others, 1983). Unit KJs is described as interbedded lithic graywacke, silty sandstone, black shale , and local conglomerate. Irregular quartz segregations and veinlets are locally present. Scattered stocks and locally abundant dikes of intermediate to felsic composition intrude these sedimentary rocks. Adjacent to some of the larger igneous bodies are narrow contact aureoles of pelitic hornfels. Unit KJs is intruded (locally) by various Cretaceous to Tertiary plutons. The plutons include quartz monzonite, grano-diorite, diorite, and rhyolite dikes. Also present is Unit Tv of Nelson and others (1983) which includes rhyolitic breccia, ash-flow tuff, flows, and intrusive rocks and subordinate mafic to intermediate flows. Potassium-argon ages for unit Tv range from 56.2 to 62.7 m.y. (Eakins and others, 1978).
Geologic map unit (-155.695238597808, 60.4703086454717)
Mineral deposit model Placer Au (Cox and Singer, 1986; model 39a)
Mineral deposit model number 39a
Age of mineralization The placer gold is Quaternary, the source of gold could come from a variety of rocks with diverse ages.
Alteration of deposit Not applicable

Production and reserves

Workings or exploration Three placer gold claims noted in 1973 by the U.S. Bureau of Mines.
Indication of production Undetermined
Reserve estimates No reserves
Production notes No production

Additional comments

Cobb and Reed (1981) mention gold in most river bars of the Mulchatna River, with most prospecting occurring around the late 1890s or early 1900s.

References

MRDS Number A106349

References

U.S. Bureau of Mines, 1973, Alaska 1:250,000-scale quadrangle map overlays showing mineral deposit locations, principal minerals, and number and type of claims: U.S. Bureau of Mines Open-File Report 20-73, 95 overlays (updated in 1986, 1987).
Reporters D.P. Bickerstaff (USGS)
Last report date 6/15/1998