Porcupine Creek

Occurrence, Inactive

Commodities and mineralogy

Main commodities Ag; Au
Ore minerals arsenopyrite; galena; gold
Gangue minerals calcite; quartz

Geographic location

Quadrangle map, 1:250,000-scale SR
Quadrangle map, 1:63,360-scale B-7
Latitude 60.3021
Longitude -149.447
Nearby scientific data Find additional scientific data near this location
Location and accuracy The occurrence is located a mile west of Porcupine Creek and three-quarters of a mile southeast of peak 3722. It is in the SE1/4 section 33, T. 3 N., R. 1 W., of the Seward Meridian, at an elevation of 3,000 feet. This is location S-212 of Jansons and others (1984). This location is accurate to within a quarter of a mile.

Geologic setting

Geologic description

Mineralization consists of several quartz veins containing minor amounts of sulfide minerals. One vein in a small gulch is 1 to 3 feet wide; it contains calcite and minor arsenopyrite (Hoekzema and Sherman, 1983). The host rock is iron-stained slate on the footwall; foliation strikes N10E and dips 85E. The hanging wall is metasandstone. Several 1- to 3-inch-thick veins are located 200 to 300 feet south and 200 feet above the large vein. These smaller veins are hosted in graywacke and strike N75W and dip 85N. They contain considerable arsenopyrite and minor galena. The host rock is slate and graywacke of the Valdez Group of Late Cretaceous age (Nelson and others, 1985). Three samples assayed trace amounts of gold and as much as 0.2 ounce of silver per ton (Jansons and others, 1984).
Geologic map unit (-149.449154619719, 60.3015384166309)
Mineral deposit model Low-sulfide Au-quartz veins (Cox and Singer, 1986; model 36a)
Mineral deposit model number 36a
Age of mineralization Cretaceous or younger; the veins cut rocks of the Valdez Group of Late Cretaceous age.
Alteration of deposit The slate in the footwall is iron-stained.

Production and reserves

Workings or exploration There are no workings or improvements described in the literature. Three samples assayed trace amounts of gold and as much as 0.2 ounce of silver per ton (Jansons and others, 1984).
Indication of production None

References

References

Reporters Jeff A. Huber and Carol S. Huber (Anchorage)
Last report date 6/21/2001