Erickson; Erickson and Madden Mine, Nizina Mining District, Valdez-Cordova Census Area, Alaska, USAi

Regional Level Types
Erickson; Erickson and Madden Mine	Mine
Nizina Mining District	Mining District
Valdez-Cordova Census Area	Census Area
Alaska	State
USA	Country

The locality is in the Wrangell-Saint Elias National Park and Preserve.
Location: 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).
Geology: 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).
Workings: The deposit was developed on 3 levels by about 300 feet of underground workings accessed from two adits.
Age: 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: Quartz-epidote veining and replacement.
Production: A small amount of copper was produced in 1917.

Commodities (Major) - Cu; (Minor) - Ag
Development Status: Yes; small
Deposit Model: Basaltic Cu (Cox and Singer, 1986; model 23)

Other Databases

Link to USGS - Alaska:	MC159

Other Regions, Features and Areas containing this locality

References