Rambler; Golden Eagle Group; Cliff vein Prospect, Chisana Mining District, Valdez-Cordova Census Area, Alaska, USAi

Regional Level Types
Rambler; Golden Eagle Group; Cliff vein Prospect	Prospect
Chisana Mining District	Mining District
Valdez-Cordova Census Area	Census Area
Alaska	State
USA	Country

The mine is in the Wrangell-St. Elias National Preserve.
Location: This prospect is low on the east flank of White Mountain. It is at an elevation of about 3,600 feet, 4,500 feet north-northeast of Nabesna. The site is in the SE1/4 of section 16, T. 7 N., R. 13 E. of the Copper River Meridian. This is locality M2 of Lowe and others (1982), locality 12 of Richter and others (1975), and National Park Service locality WRST-13 (unpublished data). Cobb and Richter (1980) included this prospect under the name 'Nabesna (Mining Corp.)'. It is located to within a few hundred feet.
Geology: A surface exposure of massive pyrrhotite with some pyrite and late marcasite was discovered at this prospect in 1940 (Wayland, 1943). The massive pyrrhotite was exposed over a length of 52 feet, a vertical distance of 34 feet, and a width of 19 feet. The pyrrhotite is coarse grained; some crystal are 2 inches in diameter. The pyrrhotite also forms crystals in vugs and Wayland (1943) observed minor chalcopyrite and late marcasite under the microscope. Wayland (1943) reported that 14 samples of the massive sulfide assayed as much as 2.43 ounces of gold per ton and averaged 0.92 ounce of gold per ton (assuming a gold price of $35.00 per ounce). The massive sulfide body replaces Triassic limestone peripheral to a mid-Cretaceous granodiorite and quartz diorite stock (Lowe and others, 1982). Skarn assemblages are exposed about 3,000 feet to the southwest at the Nabesna mine (NB022) where calcic skarn containing abundant garnet and pyroxene and magnesian skarn containing magnetite and serpentine are well developed (Weglarz, 1991; Newberry and others, 1997). Chalcopyrite and other sulfide minerals are common in the calcic skarn and Newberry and others (1997) consider the principal deposits in the area to be gold-rich copper skarns. A concordant biotite/hornblende K/Ar date for the intrusive rocks is 114 +/- 3.4 Ma (Richter, Lanphere, and Matson, 1975).
Workings: This deposit is exposed at the surface and has probably been explored by diamond drilling and and other techniques since its discovery in 1940 . It was an active prospect as recently as the 1980s (Lowe and others, 1982).
Age: Mid-Cretaceous. A concordant biotite/hornblende K/Ar date for the intrusive rocks is 114 +/- 3.4 Ma (Richter, Lanphere, and Matson, 1975).
Alteration: Oxidation. Marcasite replacement of pyrrhotite.

Commodities (Major) - Au; (Minor) - Cu
Development Status: Undetermined.
Deposit Model: Cu skarn (Cox and Singer, 1986; model 18b)

Other Databases

Link to USGS - Alaska:	NB023

Other Regions, Features and Areas containing this locality

References