Peterson

Prospect, Undetermined

Alternative names

Surprise

Commodities and mineralogy

Main commodities Ag; Au; Cu; Pb; Zn
Ore minerals chalcopyrite; galena; pyrite; pyrrhotite; sphalerite
Gangue minerals calcite; graphite; quartz

Geographic location

Quadrangle map, 1:250,000-scale KC
Quadrangle map, 1:63,360-scale B-5
Latitude 55.365
Longitude -131.474
Nearby scientific data Find additional scientific data near this location
Location and accuracy The Peterson prospect is just above sea level on the west shore of George Inlet, about 1.15 miles south of the mouth of Beaver Falls Creek. The site is in section 17, T. 75 S., R. 92 E., of the Copper River Meridian. It corresponds to loc. 80 in Elliott and others (1978), and to loc. 296 in Maas and others (1995). The location is accurate within a few hundred feet. Some early reports apparently refer to this property as the Surprise prospect (Cobb and Elliott, 1980, p. 84).

Geologic setting

Geologic description

The country rocks in this part of Revillagigedo Island are marine, pelitic phyllite and schist that are intruded by Cretaceous stocks, sills, and dikes of feldspar-porphyritic granodiorite, and by a stock and probably related plugs of Tertiary gabbro (Berg and others, 1988). The strata and some of the granodiorite were regionally metamorphosed to greenschist grade in Late Cretaceous time. These regionally metamorphosed rocks subsequently were locally contact metamorphosed to hornblende hornfels near the contacts of Cretaceous granodiorite plutons that were emplaced after the regional metamorphism, and then more widely remetamorphosed to hornblende hornfels near the contacts of the Tertiary gabbro. The premetamorphic age range of the pelitic strata is uncertain. Berg and others (1988) assign them a Mesozoic or (Late) Paleozoic age; Brew and Ford (1998) and Crawford and others (2000) assign them to the Gravina belt, of Late Jurassic or Cretaceous age.
Wright and Wright (1908, p. 150) described the principal Peterson deposit as a fault-gouge-bounded, sulfide-bearing, quartz-calcite-graphite fissure vein that averages 15 feet wide and has been traced along strike for 1000 feet. The vein strikes NW, parallel to the foliation of pelitic schist host rock, and dips steeply NE to vertical, which intersects the SW dip of the foliation. The sulfide minerals in the vein are pyrite, galena, sphalerite, and pyrrhotite, along with reported values of Au and Ag. Pyrite is also sparsely disseminated in the wallrocks adjacent to the vein.
The Peterson deposit was discovered in 1908 and explored by 3 short adits in 1913. There has been no additional mining-related work since then (Maas and others, 1995, p. 202). In 1995, the patented property was on the site of the George Inlet Lodge. Samples of a shear zone exposed in an adit showed low metal values (Maas and others, 1995, p. 209). A sample of massive pyrrhotite collected from the creek adjacent to this adit contained 6.2 ppm Ag, 1066 ppm Cu, 2469 ppm Zn, and 246 ppm Ni.
Geologic map unit (-131.47568818944, 55.3646538686099)
Mineral deposit model Polymetallic veins (Cox and Singer, 1986; model 22c)
Mineral deposit model number 22c
Age of mineralization Probably Late Cretaceous or younger.
Alteration of deposit Pyrite is sparsely disseminated in the schist wallrock adjacent to the vein.

Production and reserves

Workings or exploration The Peterson deposit was discovered in 1908 and explored by 3 short adits in 1913. There has been no additional mining-related work since then (Maas and others, 1995, p. 202). In 1995, the patented property was on the site of the George Inlet Lodge. Samples of a shear zone exposed in an adit showed low metal values (Maas and others, 1995, p. 209). A sample of massive pyrrhotite collected from the creek adjacent to this adit contained 6.2 ppm Ag, 1066 ppm Cu, 2469 ppm Zn, and 246 ppm Ni.
Indication of production None

References

MRDS Number A012335

References

Reporters H.C. Berg, USGS
Last report date 7/3/1999