Limestone Creek

Mine, Inactive

Alternative names

Lake Creek
Lime Creek

Commodities and mineralogy

Main commodities Au
Other commodities Ag; Cr; Cu; Pb; PGE; W
Ore minerals chromite; galena; gold; native copper; native silver; pge; pyrite; scheelite
Gangue minerals garnet; olivine; magnetite

Geographic location

Quadrangle map, 1:250,000-scale MH
Quadrangle map, 1:63,360-scale A-2
Latitude 63.1323
Longitude -144.6428
Nearby scientific data Find additional scientific data near this location
Location and accuracy Limestone Creek, formerly named Lake Creek and also called Lime Creek, is a tributary of the Middle Fork Chistochina River. The Limestone Creek placer mine is about 0.1 mile northeast of the present course of Limestone Creek. The deposit was mined over a distance of about 0.8 mile. The mine is near the southeast corner of section 34, T. 20 S., R. 16 E., Fairbanks Meridian. Limestone Creek is locality 28 on figure 6 of Cobb (1979 [OFR 79-238]) and is included with nearby deposits as locality 68 of MacKevett and Holloway (1977). The mine corresponds generally to locality 13 in table 3 of Nokleberg and others (1991).

Geologic setting

Geologic description

Limestone Creek is the main placer deposit in the drainage of the Middle Fork Chistochina River; minor gold-bearing creeks such as Bedrock Creek (MH310) and Kramer or Kraemer Creek (MH311), also tributaries of the Middle Fork, are sometimes lumped with the Limestone Creek deposit.
Mining on Limestone Creek mainly took place on a bench on the north side of and subparallel to modern Limestone Creek. The gravels generally consist of about 35 to 45 feet of boulder-gravel wash underlain by a blue-gray glacial clay. The best 'pay' is in an iron-stained gravel zone on clay false bedrock (Moffit, 1912). Locally the gravel section is as much as 70 feet thick (Moffit, 1944).
This placer deposit is not an alluvial deposit of Limestone Creek but is a bench deposit on the west side of the Middle Fork Chistochina River.
The deposit is in post-glacial and outwash gravels deposited on a slightly irregular bedrock floor that was scoured by ice moving from the north and west. Gravel, cobble, and boulder deposits contain transported granite and schist that are intermixed with bedrock materials of local origin. A source of some exotic materials and possibly gold was recognized in a gravel exposed about a mile north of the Limestone Creek mine site. As described by Moffit (1944), the gravel resembles the 'round wash' conglomerate of Tertiary age.
Drilling disclosed that the gold was scattered through the bench gravels but was enriched near bedrock; gold-bearing gravel was fairly well stratified and, at one place, formed two gold-bearing gravel layers separated by a compacted gravel false bedrock (Moffit, 1944).
The placer gold is fairly fine grained. Placer concentrates also contain shot size and large (2 to 3 pounds) fragments of native copper and galena and lesser amounts of chromite, platinum group elements (PGE), pyrite, scheelite, and some native silver. The occurrence of platinum metals was also noted by Chapin (1919) and Rose (1967). Olivine and magnetite occur in the concentrates (Moffit, 1944). Moffit (1912) proposed a local bedrock source for copper but a distal source for gold.
Geologic map unit (-144.645030874305, 63.1319074210324)
Mineral deposit model Placer Au-PGE (Cox and Singer, 1986; model 39a).
Mineral deposit model number 39a
Age of mineralization Pleistocene.

Production and reserves

Workings or exploration Mining began on Limestone Creek in 1908 (Moffit, 1909). The mine was active intermittently until 1942, but during many years the main activity was prospecting and drilling. A ten-man operation was reported in 1922 (Brooks and Capps, 1924). A major exploration program began in about 1934 (Moffit, 1937). Holes were drilled on 100-foot centers on five northwest-trending lines spaced 450 feet apart (Moffit, 1944); the deposit was also explored with pits and shafts. The deposit was prepared for mining in the late 1930s and 1940; the work included 5,900 feet of new ditches and an 800-foot-long dead cut to allow placement of sluice boxes for the hydraulic operation. An extensive operation began in 1941 to mine the demonstrated resource. Some gold was recovered, but the operation was terminated by World War II (Moffit, 1954). Some of the resource may have been mined in the late 1970s and early 1980s during a period of high gold price.
Indication of production Yes
Reserve estimates There probably is a low-grade but possibly large gold resource in bench gravel on the west side of the Middle Fork Chistochina River.
Production notes Limestone Creek produced at least 580 ounces of placer gold in and before 1934 (Moffit, 1944). It probably has a total production of more than 1,000 ounces.

References

MRDS Number M045387

References

Reporters W.T. Ellis (Alaska Earth Sciences), C.C. Hawley (Hawley Resource Group), and W.J. Nokleberg (USGS)
Last report date 12/28/2001