Ann

Prospect, Inactive

Commodities and mineralogy

Main commodities Ag; Cu; Pb; Zn
Other commodities As; Au
Ore minerals arsenopyrite; azurite; chalcopyrite; galena; malachite; pyrite; pyrrhotite; sphalerite
Gangue minerals barite; quartz

Geographic location

Quadrangle map, 1:250,000-scale WI
Quadrangle map, 1:63,360-scale B-6
Latitude 67.3954
Longitude -152.8472
Nearby scientific data Find additional scientific data near this location
Location and accuracy The Ann prospect is located 3.5 miles east-northeast of the east end of Ernie Lake and about 3.5 miles northwest of the junction of Pass Creek and Mettenpherg Creek. The coordinates mark the principal mineral showing; it is on an unnamed creek at an elevation of about 580 meters, near the center of section 26, T. 30 N., R. 24 W. There are other mineral showings up to 500 feet upstream and downstream from the main showing. The location is accurate.

Geologic setting

Geologic description

This prospect consists of vein and stratabound(?) Pb-Zn deposits of massive, stringer, and disseminated sulfides in pelitic schist interbeds in the Devonian Skajit Limestone, adjacent to the Ernie Lake granitic plutons (Nokleberg and others, 1996). The principal mineral showing at the Ann prospect is a steeply-dipping lens of massive pyrite, sphalerite, galena and minor chalcopyrite at a contact between graphitic quartz schist and sericite-talc schist (Kurtak and others, 1999). The lens is 4-5 feet thick and is exposed for only about 6 to 7 feet before pinching out in one direction and disappearing under cover in the other. A chip sample across this lens contained 3.34 percent lead, 4.31 percent zinc, 2.64 ounces of silver per ton, and 2.5 parts per million (ppm) gold (Kurtak and others, 2002). Bedded quartz-barite rock occurs a few hundred feet from the main Pb-Zn showing, but it contains no sulfides.
Several similar, but smaller, deposits are within a few hundred feet of the main showing. One of these consists of pyrite, arsenopyrite, pyrrhotite(?), galena, and chalcopyrite in layers and veins in calcareous, quartz-mica schist near the contact of granite gneiss and marble. A sample contained 37.7 ppm silver, 13 percent arsenic, 3.8 percent lead, 1.8 percent zinc, and 315 ppm antimony (Dillon and others, 1981: sample 480). Secondary copper carbonates, malachite and azurite, occur in the marble, calc-schist, and pelitic schist layers.
Claims were staked in 1975 (Grybeck, 1977). Exploration by industry included surface rock sampling, geologic mapping, geochemical soil sampling, hand trenching, and ground geophysics. There was also limited surface rock sampling by government agencies in the 1980s and 1990s (Dillon and others, 1981; Kurtak and others, 1999, 2002).
Geologic map unit (-152.849964967102, 67.3949303851756)
Mineral deposit model (Metamorphosed) Polymetallic vein? (Cox and Singer, 1986; model 22c?) or metamorphosed sulfide deposit (Nokleberg and others, 1987).
Mineral deposit model number 22c?
Age of mineralization Devonian or younger based on the age of the host rock.
Alteration of deposit Oxidation of copper mineral(s).

Production and reserves

Workings or exploration Claims were staked in 1975 (Grybeck, 1977). Exploration by industry included surface rock sampling, geologic mapping, geochemical soil sampling, hand trenching, and ground geophysics. There was also limited surface rock sampling by government agencies in the 1980s and the 1990s (Dillon and others, 1981; Kurtak and others, 1999, 2002).
Indication of production None
Reserve estimates None.
Production notes None.

Additional comments

See also Buzz (WI047).

References

MRDS Number A011996

References

BP Alaska Exploration Inc., 197, Annual progress report, 1978, BP General Crude Joint Venture Buzz-Ann-Dome property: unpublished report, 4 p. (held by the Bureau of Land Management, Anchorage, Alaska).
Kurtak, J.M., Klieforth, R.F., Clark, J.M., and Maclean, E.A., 2002, Mineral investigations in the Koyukuk mining district, northern Alaska: Final Report: U.S. Bureau of Land Management Technical Report 50, v. 1 and 2, 845 p.
WGM Inc., 1977, Annual progress report, 1976, Buzz-Ann-Dome property, WAK-2 project: Unpublished report, 21 p. (held by Bureau of Land Management, Anchorage, Alaska.)
WGM Inc., 1978, 1977 annual progress report, Wiseman area, WAK-1 project: Unpublished report, 35 p. (held by the Bureau of Land Management, Anchorage, Alaska).
Reporters J.M. Britton (Anchorage); D.J. Grybeck (Contractor, USGS)
Last report date 2/1/2011