Ruby Gulch

Mine, Inactive

Alternative names

Jackpot

Commodities and mineralogy

Main commodities Au
Ore minerals gold

Geographic location

Quadrangle map, 1:250,000-scale MH
Quadrangle map, 1:63,360-scale A-2
Latitude 63.159
Longitude -144.7681
Nearby scientific data Find additional scientific data near this location
Location and accuracy This mine is at an elevation of about 4,250 feet in Ruby Gulch, a tributary of the Chisna River. The mine is in the NW1/4NW1/4 section 30, T. 20 S., R. 16 E., Fairbanks Meridian, probably near the Jackpot mine site shown by Mendenhall and Schrader (1903). Those geologists described two mining localities, one near the mouth of the creek and the second in the canyon of Ruby Gulch on the Jackpot claim. Ruby Gulch is locality 24 on figure 6 of Cobb (1979 [OFR 79-238]) and locality 10 in table 3 of Nokleberg and others (1991).

Geologic setting

Geologic description

Ruby Gulch is mainly in argillite of the Slana Spur Formation of Pennsylvanian and Early Permian (?) age (Richter and Dutro, 1975; Nokleberg and others, 1991). Chapin (1919) previously assigned the argillite to the Mankomen Formation. Near the head of the creek, a section of 'round wash' conglomerate of Tertiary age has been downfaulted into the Slana Spur Formation (Chapin 1919).
On lower Ruby Creek the placer apparently is a reworked alluvial fan. Placer gold occurred in 3 to 4 feet of gravel on clay false bedrock in a channel cut in the alluvial fan. Upstream on the Jackpot claim 2 to 4 feet of rich gravel were mined from a narrow canyon (Mendenhall and Schrader, 1903) in a section of creek that also had a parallel lower grade channel incised in bedrock (Moffit, 1912). Pay gravel consists mainly of argillite derived from local bedrock but includes greenstone and granitic boulders from the 'round wash' conglomerate, the probable ultimate source of most of the gold.
Gold in Ruby Gulch is reported to be similar to that in Miller Gulch (MH296) and to occur in nuggets weighing as much as about 0.6 ounce. Fineness reported is about 870 to 900 (Mendenhall and Schrader (1903).
Geologic map unit (-144.770329627473, 63.1586051967234)
Mineral deposit model Placer Au (Cox and Singer, 1986; model 39a).
Mineral deposit model number 39a
Age of mineralization Tertiary ('round wash'), Pleistocene (?) and Holocene.

Production and reserves

Workings or exploration In 1902, Ruby Gulch was being mined in two places, one near the mouth of the creek, the other upstream in the canyon of Ruby Gulch (Mendenhall and Schrader, 1903). In 1910, Ruby Creek was the third most important placer creek in the district after Miller Gulch (MH296) and Slate Creek (MH295, MH298) (Moffit, 1912), but it was mined out fairly quickly.
Indication of production Yes; small

References

MRDS Number A011778

References

Reporters W.T. Ellis (Alaska Earth Sciences), C.C. Hawley (Hawley Resource Group), and W.J. Nokleberg (USGS)
Last report date 12/5/2001