American Eagle

Occurrence, Probably inactive

Commodities and mineralogy

Main commodities Au
Other commodities As; Bi; Mo; Te
Ore minerals gold
Gangue minerals quartz; sericite

Geographic location

Quadrangle map, 1:250,000-scale EA
Quadrangle map, 1:63,360-scale B-6
Latitude 64.4366
Longitude -143.8524
Nearby scientific data Find additional scientific data near this location
Location and accuracy The American Eagle prospect is located 5 miles northeast from the of Eisenmenger Fork, Goodpaster River; about 0.1 mile southeast from the center of section 21, T. 5 S., R. 20 E., of the Fairbanks Meridian. This location is approximate although probably accurate to within one mile.

Geologic setting

Geologic description

The American Eagle occurrence is located in the eastern edge of the Goodpaster Mining District, and it was discovered in 2007 during exploration work for Rubicon Minerals by Avalon Development Corp by a sampling program including steam sediment, pan concentrate samples, and rock sampling in the area.
The primary host rocks at the American Eagle prospect is Cretaceous(?) age unfoliated biotite granite and biotite quartz monzonite. These rocks are fine- to medium-grained, equigranular and contain abundant quartz and biotite. There are numerous dikes of this biotite granite-quartz monzonite cutting the gneissic country rocks. Sulfide-bearing auriferous sheeted white quartz veins ranging from 0.1 to 1.0 cm thick are hosted in dikes of this unit. Vein material makes up 5 percent-10 percent of the country rock over an area of 400 by 50 meters. Quartz veins at American Eagle host extremely course grained bismuthinite in flat,sometimes deformed tabular plates ranging up to 1.0 cm in maximum dimensions. The bismuth-bearing veins have not been seen in outcrop and occur on a coarse boulder-strewn talus slope just below a flat ridge line. Limited grab sampling along this ridge has returned gold values ranging from trace to 3.03 gpt gold, up to 3,880 ppm bismuth, up to 5,610 ppm arsenic and up to 494 ppm molybdenum. The full extent of this mineralization is unknown due to extensive talus cover (Freeman, 2014).
Samples from a quartz boulder train and from steam sediment and pan concentrate samples in surrounding drainages in 2006 identified a 10 kilometer by 7.0 kilometer, greater than 100 ppm arsenic stream silt and pan concentrate anomaly within which samples of quartz veins interpreted as bedrock or sub-crop returned anomalous gold (from trace up to 12 gpt) (Freeman, 2014).
Assays of grab rock samples collected in 2007 returned gold values from trace to 19.1 gpt with 17 percent of samples (total 114 rock samples) containing gold in excess of 1.0 gpt gold with an average of 5.2 gpt gold (Freeman, 2014).
Geologic map unit (, )
Mineral deposit model Gold-quartz veins that contain bismuth and tellurium? (Cox and Singer, 1986; model 22c?)
Mineral deposit model number 22c?
Age of mineralization Cretaceous or younger based on age of host rock (Freeman, 2014).
Alteration of deposit Moderate to weak sericite alteration adjacent to sugary textured quartz veins which host the gold mineralization (Freeman, 2014).

Production and reserves

Workings or exploration The American Eagle occurrence was discovered during regional pan concentrate and stream sediment sampling conducted by Avalon Development Corp. for Evanachan Ltd. in the fall of 2006. Follow up rock and grab samples were collected that year (Freeman, 2014).
Indication of production None

References