Unnamed (near Deer Bay)

Prospect, Active?

Commodities and mineralogy

Main commodities Ag; Au; Cu; Pb; Zn
Ore minerals chalcopyrite; pyrite; sphalerite
Gangue minerals quartz

Geographic location

Quadrangle map, 1:250,000-scale CR
Quadrangle map, 1:63,360-scale B-2
Latitude 55.26567
Longitude -132.66673
Nearby scientific data Find additional scientific data near this location
Location and accuracy This prospect is near the shoreline of upper Hetta Inlet about 0.4 mile west of Dell Island. It is in the NE1/4 section 20, T. 76 S., R. 84 E. Informally, it is sometimes called the 'Deer Island exhalite' (e.g., Hedderly-Smith, 1999 [Inventory]), although it is about 2 miles north of the mouth of Deer Bay and there is no nearby Deer Island on the USGS topographic maps. The mineralization is exposed along a logging road parallel to the shoreline at an elevation of about 100 feet.

Geologic setting

Geologic description

This prospect was identified as a massive sulfide deposit by Sealaska geologists in 1988, and mapped and sampled by the American Copper and Nickel Company in 1991 and 1993 (Maas and others, 1995; Hedderly-Smith, 1999 [Inventory]). There is a short adit near the shoreline that indicates earlier work not described in the literature.
The rocks in the vicinity consist of quartz-sericite-chlorite schist and metabasalt of the Wales Group of Late Proterozoic and Cambrian age that are cut by rhyodacite porphyry and diabase dikes and sills (Herreid and others, 1978; Maas and others, 1995; Hedderly-Smith, 1999 [Inventory]). The metamorphic rocks strike northeast and dip northwest. The deposit consists of a stratabound, exhalite zone up to 35 feet thick with pyrite, chalcopyrite, and sphalerite; the zone can be traced for about 1,100 feet along strike. The average value of a set of samples across the zone was 2,345 parts per million (ppm) copper, 2,263 ppm zinc, 5.7 ppm silver, and 309 parts per billion gold (Hedderly-Smith, 1999 [Inventory]).
Geologic map unit (-132.668382985535, 55.2653185604048)
Mineral deposit model Kuroko massive sulfide (Cox and Singer, 1986; model 28a).
Mineral deposit model number 28a

Production and reserves

Workings or exploration Sampling of mineralization in outcrops along a logging road in the late 1990s, as well as geologic mapping and geochemical sampling. A short adit nearby was probably driven in the early 1900s.
Indication of production None

Additional comments

This prospect is on land that has been conveyed to the Sealaska Corporation or is under application for transfer to them.

References

References

Hedderly-Smith, D.A., 1989, Report of the 1988 field season - Sealaska Mineral Reconnaissance Project: Sealaska Corporation, 66 p. (Unpublished report held by the Sealaska Corporation, Juneau, Alaska.)
Hedderly-Smith, D.A., 1990, Report of the 1989 field season - Sealaska Mineral Reconnaissance Project: Sealaska Corporation, 58 p. (Unpublished report held by the Sealaska Corporation, Juneau, Alaska.)
Hedderly-Smith, D.A., 1991, Report of the 1990 field season-Sealaska Mineral Reconnaissance Project: Sealaska Corporation: Sealaska Corporation, 2 vols., 180 p., 13 plates. (Unpublished report held by the Sealaska Corporation, Juneau, Alaska.)
Hedderly-Smith, D.A., 1992, Report of the 1991 field season - Sealaska Mineral Reconnaissance Project: Sealaska Corporation, 2 vols., 225 p. 23 plates. (Unpublished report held by the Sealaska Corporation, Juneau, Alaska.)
Hedderly-Smith, D.A., 1999, Inventory of metallic mineral prospects, showings and anomalies on Sealaska lands, 1988 through 1998: Sealaska Corporation, Juneau, Alaska, 217 p. (internal report held by Sealaska Corporation, Juneau, Alaska).
Reporters D.J. Grybeck (Applied Geology)
Last report date 5/1/2004