| Quadrangle map, 1:250,000-scale | JU |
|---|---|
| Quadrangle map, 1:63,360-scale | D-4 |
| Latitude | 58.8493 |
| Longitude | -135.0722 |
| Nearby scientific data | Find additional scientific data near this location |
| Location and accuracy | The Cumberland prospect is at an elevation of about 2,250 feet, about 3 miles east of Pt. Sherman on Lynn Canal and 2 miles south-southwest of Lions Head Mountain in the Kakuhan Range. It is at the head of Sherman Creek in the E1/2 section 9, T. 35 S., R. 62 E. of the Copper River Meridian. The location is accurate. |
Geologic descriptionNote: Beginning in the 1990s, this and other old mines and prospects in the vicinity were consolidated by Coeur-Alaska into a single property (Birak, 2006). They have carried out major new drilling and underground exploration that better defines the mineralization, largely blurs the geologic distinction among the old deposits, and extends the ore bodies greatly. They have developed a coherent modern interpretation of the mineralization as a single deposit which Coeur-Alaska intends to mine as a unit. This deposit is described separately in ARDF as the Kensington (Coeur-Alaska) deposit (JU261). For geologic reference purposes and for their historic value, the pre-Coeur-Alaska data for this and the other old mines and prospects that Coeur-Alaska consolidated are retained in ARDF. The Cumberland prospect was probably developed before 1909. Workings include a 54-foot adit and an open cut. The adit exposes gray phyllite and felsic phyllite. Thin quartz veins containing minor pyrite occur near the portal and in a small shear near the face of the adit. Although native gold in quartz veins has been identified in dump samples by other workers in the area, U.S. Bureau of Mines samples all contained less than 0.1 part per million gold (Redman and others, 1989). | |
| Geologic map unit | (-135.074016128837, 58.8489710605669) |
|---|---|
| Mineral deposit model | Low-sulfide Au-quartz vein (Cox and Singer, 1986; model 36a). |
| Mineral deposit model number | 36a |
| Age of mineralization | The age of mineralization in the Berners Bay district is about 55 Ma, the same as the other mesothermal gold-quartz-vein deposits in the Juneau Gold Belt (Goldfarb and others, 1997). |
| Workings or exploration | The Cumberland prospect was probably developed before 1909 by a 54-foot adit and an open cut. |
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| Indication of production | None |
ReferencesBirak, D.J., 2006, Kensington gold project: Unpublished Technical Report for Cour d'Alene Mines, 116 p. (posted on www/.sedar.com, April 20, 2006).
Goldfarb, R.J., Miller, L.D., Leach, D.L., and Snee, L.W, 1997, Gold deposits in metamorphic rocks in Alaska, in Goldfarb, R.J., and Miller, L.D., eds., Mineral Deposits of Alaska: Economic Geology Monograph 9, p. 151-190.
Miller, L.D., Goldfarb, R.J., Snee, L.W., Gent, C.A., and Kirkham, R.A., 1995, Structural geology, age, and mechanisms of gold vein formation at the Kensington and Jualin deposits, Berners Bay district, southeast Alaska: Economic Geology, v. 90, p. 343-368.
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| Reporters | J.C. Barnett and L.D. Miller (Juneau, Alaska ); D.J. Grybeck (Port Ludlow, WA) |
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| Last report date | 6/5/2008 |