Erickson

Mine, Inactive

Alternative names

Erickson and Madden

Commodities and mineralogy

Main commodities Cu
Other commodities Ag
Ore minerals chalcocite; cuprite; malachite; native copper; tenorite
Gangue minerals epidote; quartz

Geographic location

Quadrangle map, 1:250,000-scale MC
Quadrangle map, 1:63,360-scale B-4
Latitude 61.408
Longitude -142.2554
Nearby scientific data Find additional scientific data near this location
Location and accuracy This mine is on the north valley wall of lower Twaharpies Glacier. It is at an elevation of about 3,800 feet, 500 feet from of the glacier, and 5,800 feet southwest of peak 8235. The site is 700 feet south of the center of section 30, T. 5 S., R. 18 E. of the Copper River Meridian. This is locality 62 of MacKevett (1976) and it is accurately located. Cobb and MacKevett (1980) include this prospect under the name 'Erikson (and Madden)'. The mine is shown on the McCarthy B-4 topographic map (1994 edition).

Geologic setting

Geologic description

This deposit consists of native copper, tenorite, cuprite, and minor amounts of chalcocite and malachite in irregular masses, thin veins, and disseminated grains in the upper parts of Triassic Nikolai Greenstone that consists of amygdaloidal lava flows. To a lesser extent, the ore minerals occurs as fillings in amygdules or associated with quartz-epidote veins in the flows (Miller, 1946; MacKevett, 1976). Most of the native copper occurs as small grains but masses up to 50 or 60 pounds have been found. Samples of the mineralization contained up to 70 parts per million (ppm) silver and more than 20,000 ppm copper (MacKevett and Smith, 1968, samples 141-146). The mine was developed by about 300 feet of underground workings and a little copper was produced in 1917 (MacKevett, 1976). Copper mineralization is common in Nikolai Greenstone and is thought to have accompanied regional deformation and low-grade metamorphism in the Late Jurassic to Early Cretaceous (MacKevett and others, 1997).
Geologic map unit (-142.25745138086, 61.4075833355429)
Mineral deposit model Basaltic Cu (Cox and Singer, 1986; model 23)
Mineral deposit model number 23
Age of mineralization Cretaceous? Copper mineralization is common in Nikolai Greenstone and is thought to have accompanied regional deformation and low-grade metamorphism in the Late Jurassic to Early Cretaceous (MacKevett and others, 1997).
Alteration of deposit Quartz-epidote veining and replacement.

Production and reserves

Workings or exploration The deposit was developed on 3 levels by about 300 feet of underground workings accessed from two adits.
Indication of production Yes; small
Production notes A small amount of copper was produced in 1917.

Additional comments

The locality is in the Wrangell-Saint Elias National Park and Preserve.

References