Willow Creek

Prospect, Active

Commodities and mineralogy

Main commodities Sb
Other commodities As; Au; Zn
Ore minerals arsenopyrite; gold; pyrite; sphalerite; stibnite
Gangue minerals quartz

Geographic location

Quadrangle map, 1:250,000-scale LG
Quadrangle map, 1:63,360-scale A-1
Latitude 65.0617
Longitude -147.4552
Nearby scientific data Find additional scientific data near this location
Location and accuracy This prospect is in the bed of Willow Creek, a tributary of Cleary Creek about 100 yards from its mouth. It is in the NE1/4 sec. 25, T. 3 N., R. 1 E., of the Fairbanks Meridian. The location is accurate

Geologic setting

Geologic description

Note: As of 2008, this site and several others in the vicinity are being explored as a single entity by Freegold Ventures Inc. (Freeman, 2008) Considerable new mineralization has been discovered that indicates this is part of a larger mineralized system that is described as a separate ARDF site (LG207).
This antimony prospect was uncovered during placer mining operations and was described by Henry Joesting in a report to the Alaska Territorial Department of Mines in 1942. The antimony ore occurs as stibnite in a zone of white quartz and gouge that strikes east-west across the valley of Willow Creek (Joesting, 1942; ATDM PE 49-7). In the hydraulic cut where the overburden and gravel had been removed, high-grade ore could be traced continuously from the west side of the cut to the creek, a distance of about 75 feet. Ore is also found on the east side of the cut, about 100 feet from the creek. Between these two showings of ore, the zone consists mainly of quartz and gouge, with minor amounts of stibnite and pyrite, and occasionally arsenopyrite. Some pieces of high-grade stibnite found on the surface measured about a foot across. Most of the ore is fine-grained and massive with a minor portion made up of coarse-bladed crystals of stibnite. The higher grade portions contained 56 percent antimony. Small amounts of pyrite and arsenopyrite occur in the lower grade material.
The bedrock is mainly a soft, badly weathered biotite schist, with considerable clay. The schist strikes east and dips steeply north. Several thin limestone beds were noted. A few of these beds about 100 feet upstream from the stibnite prospect contain sphalerite and pyrite. Numerous small veins and lenses of glassy quartz were also noted in the bedrock. Some contain small amounts of pyrite, arsenopyrite, and sphalerite.
Geologic map unit (-147.457647447591, 65.0612765419963)
Mineral deposit model Stibnite-quartz vein (Cox and Singer, 1986; model 27d).
Mineral deposit model number 27d
Age of mineralization Probably about 90 Ma based on analogy with similar gold deposits nearby.
Alteration of deposit Not stated.

Production and reserves

Workings or exploration The vein was exposed by a hydraulic cut during placer mining operations.
Indication of production None
Production notes No record of production.

References

MRDS Number A015500; D002661

References

Freeman, C.J., 2008, Executive summary report for the Golden Summit project, Fairbanks Mining District, Alaska: Unpublished Technical Report for Freegold Ventures Ltd., 112 p. (posted on www.sedar.com, March 31, 2008).
Smith, S.S., 1917, The mining industry in the territory of Alaska during the calendar year 1915: U.S. Bureau of Mines Bulletin 142, 66 p.
Reporters C.J. Freeman, J.R. Guidetti Schaefer (Avalon Development Corporation); D.J. Grybeck (Port Ludlow, WA)
Last report date 6/5/2008