Unnamed (southeast flank of White Mountain)

Mine, Inactive

Commodities and mineralogy

Main commodities Ag; Au
Ore minerals gold; limonite; pyrite
Gangue minerals quartz

Geographic location

Quadrangle map, 1:250,000-scale NB
Quadrangle map, 1:63,360-scale B-5
Latitude 62.3704
Longitude -143.0353
Nearby scientific data Find additional scientific data near this location
Location and accuracy This mine is low on southeast flank of White Mountain. It is at an elevation of about 3,750 feet, about 2,000 feet west-northwest of Nabesna. The map site is about 0.4 mile west of the center of section 21, T. 7 N., R. 13 E. of the Copper River Meridian. This is locality M4 of Lowe and others (1982), locality 14 of Richter and others (1975 ), and it is included in National Park Service locality WRST-14 (unpublished data). Cobb and Richter (1980) include this mine under the name 'Nabesna (Mining Corp.)'. It is located to within about 100 feet.

Geologic setting

Geologic description

In the early 1900s, the Royal Development Co. found and briefly exploited a gossan zone developed over a gold-bearing sulfide deposit. The sulfide deposit is in a sheared intrusive rock and adjacent contact-metamorphosed limestone (Moffit and Knopf, 1909). Mining was in a surface cut where a 1- to 4-foot-wide mineralized zone was exposed. Pyrite is the dominant mineral in the deposit but if it is similar to others in the area (NB022), it probably also contains chalcopyrite, galena, and sphalerite A 16-inch-wide sample taken across the deposit assayed 0.06 ounce of gold per ton and 0.20 ounce silver per ton (Pilgrim, 1931, p. 60-61). A 3-stamp mill was erected in 1906; it processed about 60 tons of ore and reportedly recovered 0.6 ounce of gold per ton. Two adits totaling 130 feet in length were subsequently driven 200 feet below the gossan outcrop without encouraging results and the original claims were allowed to lapse in 1914. This mine is now included in the patented claim group surrounding the Nabesna mine (NB022).
Richter and others (1975) describe this deposit as a quartz diorite stock with disseminated pyrite and quartz-pyrite veins. They consider it to be a disseminated gold deposit.
The deposit is in the contact zone of a mid-Cretaceous granodiorite and quartz diorite stock that intrudes Triassic limestone and dolomite (Lowe and others, 1982). Skarn assemblages are well developed in the general area (see NB022) and include calcic skarn with abundant garnet and pyroxene, and magnesian skarn with magnetite and serpentine (Weglarz, 1991; Newberry and others, 1997). Sulfide minerals are common in the calcic skarn and magnetite is common in the magnesian skarn. Chalcopyrite and other sulfide minerals are common in the calcic skarn and Newberry and others (1997) consider the deposits in the area to be gold-rich copper skarns. The gold-bearing sulfide-rich pods, lenses, and veins are commonly small bodies localized in marble-front replacements and crosscutting shears (Newberry and others, 1997, figure 9). A concordant biotite/hornblende K/Ar date for the intrusive rocks in the area is 114 +/- 3.4 Ma (Richter, Lanphere, and Matson, 1975).
Geologic map unit (-143.03743242958, 62.3700220523037)
Mineral deposit model Cu skarn (Cox and Singer, 1986; model 18b)
Mineral deposit model number 18b
Age of mineralization Mid-Cretaceous. A concordant biotite/hornblende K/Ar date for the intrusive rocks in the area is 114 +/- 3.4 Ma (Richter, Lanphere, and Matson, 1975).
Alteration of deposit Oxidation. Calc-silicate and sulfide replacement.

Production and reserves

Workings or exploration Mining was in a surface cut where a 1- to 4-foot-wide mineralized zone was exposed. A 3-stamp mill was erected in 1906; it processed about 60 tons that contained about 0.6 ounce of gold per ton. Two adits totaling 130 feet in length were subsequently driven 200 feet below the gossan outcrop without encouraging results and the original claims were allowed to lapse in 1914. This mine is now included in the patented claim group surrounding the Nabesna mine (NB022). Exploration including diamond drilling occurred during the 1980s in the area.
Indication of production Yes; small

Additional comments

The mine is in the Wrangell-St. Elias National Preserve.

References

MRDS Number A011388

References

Newberry, R.J., Allegro, G.L., Cutler, S.E., Hagen-Levelle, D.D., Adams, D.D., Nicholson, L.C., Weglarz, T.B., Bakke, A.A., Clautice, K.H., Coulter, G.A., Ford, M.J., Myers, G.L., and Szumigala, D.J., 1997, Skarn deposits of Alaska, in Goldfarb, R.J., and Miller, L.D., eds., Mineral Deposits of Alaska: Economic Geology Monograph 9, p. 355-395.
Pilgrim, E.R., 1931, White River precinct, Snag River area, in Stewart, B.D., Report on cooperation between the territory of Alaska and the United States in making mining investigations and in inspection of mines for the biennium ending March 31, 1931: Alaska Terrirorial Department of Mines, p, 74-76.
Richter, D.H., Lanphere, M.A., and Matson, N.A., Jr., 1975, Granite plutonism and metamorphism, eeastern Alaska Range, Alaska: Geological Society of American Bulletin, v. 86, p. 819-820.
Weglarz, T.B., 1991, Skarn genesis at the Nabesna mine, southcentral Alaska: Fairbanks, University of Alaska, M.S. thesis, 173 p.
Reporters Travis L. Hudson (Applied Geology)
Last report date 11/24/2002