Unnamed (south of hill 1735)

Prospect, Active

Commodities and mineralogy

Main commodities Ag; Au; Sn
Other commodities As; B; Cu; Hg; Pb; Sb; Zn
Ore minerals gold; pyrite; stibnite
Gangue minerals quartz; sericite; tourmaline

Geographic location

Quadrangle map, 1:250,000-scale ID
Quadrangle map, 1:63,360-scale B-2
Latitude 62.366
Longitude -156.9318
Nearby scientific data Find additional scientific data near this location
Location and accuracy This prospect is about 0.3 mile south of hill 1735, near the divide between head of Granite Creek and the Little East Fork of George River. The occurrence is at an elevation of about 1,400 feet, near the southwest corner of section 5, T. 26 N., R. 41 W., of the Seward Meridian. The location is accurate.

Geologic setting

Geologic description

This deposit was originally described as a quartz breccia zone with limonite and tourmaline in hornfelsed sandstone of the Upper Cretaceous, Kuskokwim Group (Bundtzen, Miller, and Laird, 1986; Miller and Bundtzen, 1994; Miller, Bundtzen, and Gray, 2005). The zone is adjacent to a small body of biotite quartz monzonite. The mineralized breccia covers an area about 160 by 500 feet in size that is oriented northeast. The monzonite contains a stockwork of numerous small quartz-tourmaline-sericite veins. The quartz monzonite is undated, but a similar intrusive body exposed about 0.3 mile to the south has a 40K/40Ar age of 71.1 Ma . Grab samples of mineralization contained up to 1,000 parts per million (ppm) tin, 1,000 parts per billion (ppb) silver, 500 ppm copper, 350 ppm zinc, 100 ppm lead, 160 ppm arsenic, 54 ppm antimony, and 1,200 ppb mercury (McGimsey and others, 1988).
Battle Mountain Mining Company explored the property in the late 1980s and diamond drilled two holes; the results were not released. Placer Dome USA flew an aeromagnetic survey over the Upper Granite Creek area but that survey has not been made public (L.E. Wyrick, oral communication, 2003).
In 2008, Full Metals Minerals (2008) negotiated an exploration agreement on this property. The claims probably include another nearby unnamed property (ID135) with similar mineralization. They cite multiple styles of mineralization including granitic stocks with hornfelsed contact zones cut by sheeted quartz-tourmaline veins; swarms of altered rhyolite dikes and sills with disseminated sulfides; and gold-stibnite-pyrite veins along northeast-trending faults. Two samples of quartz-stibnite veins collected by Placer Dome in the mid-1990s contained 10.5 and 17.5 grams of gold per tonne, and four channel samples across an antimony-rich shear zone contained from 343 to 686 ppb gold.
Geologic map unit (-156.934191574918, 62.3653201713869)
Mineral deposit model Several styles of polymetallic gold-antimony(-tin) mineralization related to a small Cretaceous granitic stock.
Age of mineralization Possibly related to a nearby quartz monzonite intrusion that has a 40K/40Ar age of 71.1 Ma.
Alteration of deposit Development of quartz-tourmaline-sericite greisen in quartz monzonite pluton and hornfels.

Production and reserves

Workings or exploration Samples were collected by the U.S. Geological Survey and Alaska Division of Geological and Geophysical Surveys in the 1980s (McGimsey and others, 1988). Battle Mountain Mining Company explored the occurrence in the late 1980s and drilled two holes. Placer Dome U S flew an aeromagnetic survey over the Upper Granite Creek area but that survey has not been made public (L.E. Wyrick, oral communication, 2003). In 2008, held by Full Metals Minerals, who did at least some work on the property.
Indication of production None

References

References

Bundtzen, T.K., and Miller, M.L., 1997, Precious metals associated with Late Cretaceous-early Tertiary igneous rocks of southwestern Alaska, in Goldfarb, R.J., and Miller, L.D., eds., Mineral Deposits of Alaska: Economic Geology Monograph 9, p. 242-286.
Full Metal Minerals, 2008, Full Metal acquires Granite Creek gold property, Alaska: http://www.fullmetalminerals.com/s/NewsReleases.asp?ReportID=301696&_Type=News&_Title=Full-Metal-Acquires-Granite-Creek-Gold-Property-Alaska (News Release, May 15, 2008)
Szumigala, D.J., 1993, Gold mineralization related to Cretaceous-Tertiary magmatism in the Kuskokwim Mountains of west-central and southwestern Alaska: Los Angeles, University of California Ph.D. dissertation, 300 p.
Reporters T.K. Bundtzen (Pacific Rim Geological Consulting, Inc.), M.L. Miller (U.S. Geological Survey); and C.C. Hawley (Hawley Resource Group); D.J. Grybeck (Port Ludlow, WA)
Last report date 6/5/2008