Equator

Prospects, Undetermined

Alternative names

Saco

Commodities and mineralogy

Main commodities Au; Cu
Ore minerals chalcopyrite; pyrite
Gangue minerals quartz

Geographic location

Quadrangle map, 1:250,000-scale CR
Quadrangle map, 1:63,360-scale A-1
Latitude 55.22987
Longitude -132.06254
Nearby scientific data Find additional scientific data near this location
Location and accuracy The Equator and Saco prospects are adjacent to each other. The adit at the Equator prospect is at an elevation of about 350 feet, the Saco adit is at an elevation of about 200 feet. The prospects are about 2.1 miles east of the north end of Hump Island, near the southeast corner of section 32, T 76 S., R. 88 E.

Geologic setting

Geologic description

As described by Wright and Wright (1908), the main working on the Equator prospect is a 50-foot adit at an elevation of about 350 feet. The deposit consists of a quartz vein enclosing masses of limestone country rock. The vein strikes N60W and dips 50SW, parallel to the strike of the host rocks, but with a slightly different dip. The vein contains chalcopyrite and pyrite, with gold values. On the Saco prospect, a 50-foot adit is at an elevation of about 200 feet. A vein that strikes east-west varies from 4 feet thick at the portal to 2 inches thick at the face. The host rock is talc schist that strikes north and dips vertically. The vein contains pyrite and chalcopyrite, with gold values. The rocks in the area are part of the Wales Group of Late Proterozoic and Cambrian age (Eberlein and others, 1983; Brew, 1996).
Maas and others (1992) collected a 4-inch(?) chip sample across the vein in the Saco adit that contained 1,441 parts per million (ppm) copper, 0.6 ppm silver, and less than 5 parts per billion (ppb) gold. Hedderly-Smith (1999 [Inventory]) collected a representative sample of the dump of the Saco adit that contained 2.4 percent copper, 0.7 ppm silver, and 4 ppb gold. Maas and others (1991, 1992) and Hedderly-Smith (1999 [Inventory]) consider the deposit at the Equator prospect to be a mineralized breccia similar to the copper-gold deposits along the Kael-7 Mile Trend (CR188); the deposit at the adjacent Saco prospect is probably an epigenetic quartz vein.
Geologic map unit (-132.064212525197, 55.2295151307361)
Mineral deposit model The Equator prospect is probably a stratiform Au-Cu breccia zone in marble; the adjacent Saco deposit is probably a Au-Cu quartz vein.
Age of mineralization Younger than the Late Proterozoic or Cambrian country rock.
Alteration of deposit The mineralized fault zone at the Equator prospect is probably similar to the breccia deposits in the Kael-7 Mile Trend (CR188). If so, it is probably marked by silicification and dolomitization of the rock fragments in the breccia and of the country rock.

Production and reserves

Workings or exploration The Equator and Saco prospects were explored by 50-foot adits prior to 1908 and were sampled by government and industry geologists in the 1990s.
Indication of production None

References

MRDS Number A010111; A010125

References

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., 1992, Report of 1992 work in the Kael-Dolomi area-Sealaska minerals project: Sealaska Corporation, 60 p. (Unpublished report held by the Sealaska Corporation, Juneau, Alaska.)
Hedderly-Smith, D.A., 1993, Report of the 1992 field season-Sealaska minerals reconnaissance project: Sealaska Corporation, 60 p. (Unpublished report held by the Sealaska Corporation, Juneau, Alaska.)
Hedderly-Smith, D.A., 1993, Report of the 1993 work in the Brennan Bay-Kitkun Bay area-Sealaska minerals reconnaissance project, Sealaska Corporation, 45 p. (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