| Quadrangle map, 1:250,000-scale | SV |
|---|---|
| Quadrangle map, 1:63,360-scale | C-2 |
| Latitude | 59.554 |
| Longitude | -150.618 |
| Nearby scientific data | Find additional scientific data near this location |
| Location and accuracy | The Nuka Bay mine is on the northwest flank of Hill 1728 overlooking Beauty Bay. Beauty Bay is a northwest trending arm of Nuka Bay, about 65 miles southwest of Seward, Alaska. An overgrown trail begins near the first stream north of the mouth of the bay and climbs to an elevation of 1,100 feet where the portal and mill site are located. This is Cobb's (1972, MF-397) location 21 and Richter's (1970) location 4. Cobb summarized the relevant references under the name Nuka Bay Mines Co. This location is accurate to within 300 feet. |
Geologic descriptionThe mineralization is hosted by slates and graywackes of the Cretaceous Valdez Group (Richter, 1970). The quartz veins that have been mined are typical of the district and consist of white crystalline quartz with various amounts of sulfides. Arsenopyrite is the dominate sulfide with minor amounts of pyrite. Gold occurs as free gold associated with arsenopyrite.
At the 1,480 foot workings a four-inch to three-foot vein has been drifted on for at least 35 feet. The vein is in a thin bedded graywacke and slate that strikes N85W and dips 82N. The vein is strongly iron stained and contains scattered lens and stringers of arsenopyrite and pyrite. A single channel sample of this vein assayed 8.8 ppm gold (Richter, 1970).
The workings at 1,180 feet elevation consists of a 30-foot-deep shaft that exposed a one- to two-feet-wide quartz vein. The vein strikes N20E and dips 30NW The vein is exposed for about 20 feet on the surface and is hosted in a thin-bedded graywacke. A random channel sample of this vein assayed 304 ppm gold (Richter, 1970). A 410 foot long exploration adit was driven at 1,120 feet elevation near the mill site. The adit was driven eastward for 270 feet where it split into two drifts to the south. All the workings are in a massive graywacke that generally strikes northward and dips 35W. About 20 feet from the portal, a 0.5 foot-wide quartz vein was followed for about 30 feet. At about 65 feet from the portal, a wider vein was followed for almost 80 feet where it appears to end in a stockwork of veins about 160 feet from the portal. This vein strikes almost east-west and dips 80S. A sample of the vein assayed 0.8 ppm gold (Richter, 1970). The original purpose of the adit was probably to intercept the veins exposed at the surface but for an unknown reason, the tunnel stopped short of this goal. | |
| Geologic map unit | (-150.620098654301, 59.5534153614701) |
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| Mineral deposit model | Low-sulfide, Au-quartz vein (Cox and Singer, 1986; model 36a) |
| Mineral deposit model number | 36a |
| Age of mineralization | Tertiary; Boden and others (1991) report other veins in the district are about 55 m.y. old. |
| Alteration of deposit | None reported although Borden and others (1991) report other veins in the Nuka Bay district show carbonization, sulfidization, sericitization, and silicification of the wall rock adjacent to the veins. |
| Workings or exploration | A 400 foot tunnel was driven prior to 1933 to test the downward extension of the veins at the 1,400 foot and 1,181 foot exposures but it failed to intercept significant veining at depth. A small Gibson mill was erected prior to 1933 (Pilgrim, 1933). Two shallow shafts were dug at 1,400 feet and 1,180 feet elevation. Twenty-four tons of ore from one of these shafts produced 27 ounces of retort (Pilgrim, 1933). Channel samples at an unknown location by Pilgrim (1933) returned up to 4.54 ounces of gold per ton. Richter (1970) sampled the 1,400 foot elevation exposure which assayed 8.8 ppm gold; a two foot channel sample at the 1,180 foot exposure contained 304 ppm gold. |
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| Indication of production | Yes; small |
| Reserve estimates | None. |
| Production notes | This property has produced some gold but the exact amount is unknown. |
Additional commentsThis prospect is within Kenai Fjords National Park; the area is now closed to mineral entry. | |
| MRDS Number | A010575 |
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ReferencesPilgrim, E.R., 1933, Nuka Bay district, in Stewart, B. D., Making mining investigations and mine inspection in Alaska, biennium ending March 31, 1933: Alaska Territorial Department of Mines Annual Report 1933B, p. 26-51.
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| Reporters | Jeff A. Huber (Anchorage) |
| Last report date | 2/15/1999 |