Tourmaline Ridge

Occurrence, Inactive

Commodities and mineralogy

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

Geographic location

Quadrangle map, 1:250,000-scale EA
Quadrangle map, 1:63,360-scale B-6
Latitude 64.402
Longitude -143.987
Nearby scientific data Find additional scientific data near this location
Location and accuracy The Tourmaline Ridge occurrence is located 1 mile northeast of the Eisenmenger Fork, Goodpaster River; about 0.5 mile north from the center of section 16, T. 6 S., R. 19 E., of the Fairbanks Meridian (Freeman, 2014). This location is approximate, although probably, accurate to within one mile.

Geologic setting

Geologic description

The Tourmaline Ridge prospect is located in the eastern edge of the Goodpaster Mining District, and it was discovered in 2007 by Avalon Development Corporation. The upper 150 meters on this ridge, extending for about 800 meters along the ridge crest, is composed of tourmaline-bearing paragneiss containing massive tourmalinite (50 percent tourmaline) with lesser quartz veins and tourmaline-vein breccias. Numerous dikes of granite, ranging from less than 1 to 3 meters wide intrude the tourmaline-rich gneissic rocks and often contain tourmaline along the dike margins (Freeman, 2014).
Sampling of the tourmaline-rich rocks has returned weakly elevated gold (maximum 164 parts per billion (ppb)), up to 804 parts per million (ppm) bismuth and up to 2,620 ppm arsenic. The intensity and extent of tourmaline indicates that a fluid-rich intrusive-related mineralizing system is present on a large scale in the general Maple Leaf (EA9901) area (Freeman, 2014).
Geologic map unit (, )
Age of mineralization Cretaceous or younger based on age of host rock (Freeman, 2014).

Production and reserves

Workings or exploration The Tourmaline Ridge prospect was discovered in 2007 by Avalon Development Corporation. The prospect was rock sampled in 2007 and assays returned weakly elevated gold numbers (maximum 164 parts per billion (ppb)), up to 804 parts per million (ppm) bismuth and up to 2,620 ppm arsenic (Freeman, 2014).
Indication of production None

References

References

Reporters V.C. Zinno (Alaska Earth Sciences, Inc.)
Last report date 3/15/2016