Placer Deposits of Alaska GEOLOGICAL SURVEY BULLETIN 1374
The Aniak district is
the area drained by the Kuskokwim River and its tributaries above
Bethel as far as (and including) the Stony River.
The principal center of mining in the district was near Nyac, where
placer deposits on the Tuluksak River (6—8, fig. 12) and Bear
(9, 10, fig. 12) and California (8, fig. 12) Creeks and their tributaries
were mined from 1909 until the end of the 1964 season when the last
of three dredges was shut down. The source of most of the gold was
low-grade gold- and sulfide-bearing quartz veins in contact zones
between Cretaceous volcanic rocks and Tertiary granitic plutons and
in the plutons themselves. Cinnabar, probably originally assiciated
with extensively altered diabasic dikes or sills, constituted a large
part of the concentrates of a dredge operating on Bear Creek near
the mouth of Bonanza Creek (10, fig. 12). A little platinum was recovered
by some of the dredges in the area, but the amount is unknown. Less
rich and less extensive placer deposits similar to those near Nyac
were prospected or mined on Granite (5, fig. 12), Ophir (12, fig.
12), and other creeks.
Successful mining has been carried on for many years on Marvel Creek
(15, fig. 12) and, to a lesser extent, on other tributaries of the
Salmon River. The gold in the placers was derived from contact zones
between granitic plutons and clastic Cretaceous rocks. Unlike the
area near Nyac, sulfide minerals have not been reported in concentrates
or in quartz veinlets in contact zones. Until 1966, when a small dredge
was brought to Marvel Creek from Nyac, all operations were by nonfioat,
hydraulic, and hand methods. Farther south, on Canyon Creek (1, fig.
12), one of the headwaters of the Kwethluk River, there has also been
mining in practically every year since gold was discovered there in
1913. Canyon Creek crosses a contact zone, the probable source of
the gold in the placers, between a quartz porphyry body and Paleozoic
or Mesozoic clastic rocks. Hoare and Coonrad (1959a) found evidence
of prospecting or small-scale mining on Columbia (2, fig 12) and Rocky
(3, fig. 12) Creeks, but no reports of successful mining on these
or other streams in the basin of the Kisaralik River have been published.
A report of cassiterite from the Rigiagalik (Martin, 1919, p. 20)
River, another name for the Kisarauk was probably false.
After the Nyac area, the most productive part of the Aniak district
was the basin of Crooked Creek (21, fig. 12), where benches about
1 mile wide lying east and southeast of and parallel to the main stream
and its principal tributary, Donlin Creek (23, 24 fig. 12), were mined
from about 1910 until at least as recently as 1956. The gold was derived
from small quartz fracture fillings in Cretaceous graywacke and shale
near small silicified porphyritic albite rhyolite intrusive bodies.
The richest placers were on Snow and other left-limit gulches (22,
fig. 12) in which gold from the benches had been further concentrated.
In addition to gold, con¬centrates contained magnetite, garnet,
scheelite, cassiterite, pyrite, cinnabar, and stibnite. Only the gold
was saved. Julian Creek (26, fig. 12), a tributary of the George River,
drains a source area similar to that of the Crooked Creek-Donlin Creek
placers and was mined sporadically from about 1911 to 1939. Concentrate
samples contained gold, pyrite, some- cinnabar, and traces of monazite.
Other streams, such as Murray Gulch (20, fig. 12) near Napamute and
small tributaries of the Kuskokwim River between Crooked Creek and
Sleetmute (25, 27—29, fig. 12), drain geologically similar areas
and were sites of prospecting or mining before World War II, but only
Murray Gulch and New York Creek (20, fig. 12) have ever been listed
as producing streams.
In the upper Holitna River basin, gold has been recovered from Taylor
(31, fig. 12) and Fortyseven (19, fig. 12) Creeks. Cassi¬terite,
cinnabar, and pyrite accompany the gold in Taylor Creek; all were
probably derived from mineralized zones in Cretaceous clastic rocks
in the Taylor Mountains, where they were altered to hornfels around
a quartz monzonite stock, or from mineraliza¬tion associated with
small albite rhyolite intrusive bodies in the nearby Little Taylor
Mountains. Somewhat more than 2,000 ounces of gold is said to have
been recovered from Taylor Creek. Fortyseven Creek drains a ridge
on which there is a scheelite¬and gold-bearing lode in a silicified
shear zOne in graywacke and shale. Both gold and scheelite have been
recovered from placer deposits below the lode. Scheelite has also
been reported in an indefinitely described area west of the Horn Mountains
about 15 miles north of Napamute and wolframite has been reported
in float on a ridge west of Stevens Creek (30, fig. 12).
Placer cinnabar was mined from Cinnabar Creek (18, fig. 12), immediately
downstream from the Cinnabar Creek lode mine, described by Sainsbury
and MacKevett (1965, p. 38—40). Although the placer production
probably was small, it is of particular interest because it is one
of the few examples of successful primary
US Geological Paper 610
The Tuluksak-Aniak district comprises the drainage basins of the Tuluksak and Aniak Rivers between lat 60°30' and 61 °30' N. and long 159°00' to 161 °00' w. After 1900, prospectors from Nome roamed throughout the lower Kuskokwim River valley and made placer discoveries along the Innoko and Holitna Rivers and finally, in 1907 or 1908, in the Bear Creek area of the Tuluksak watershed (Maddren, 1915, p. 299-300). About 2 years later gold was found in the gravels of the Aniak River. From 1909 through 1959 the district produced 230,555 ounces of gold; however, the data for 1931-46 are incomplete. The district was active in 1959. Flood-plain and bench gravels have been productive. The gold probably has been derived from small quartz stringers in the country rock composed of sandstone, shale, agglomerate, and fine-grained tuffaceous rocks. A granitic stock cuts the sedimentary rocks and probably was responsible for the mineralization (Maddren, 1915, p. 327).