Humboldt

Mine, Inactive

Commodities and mineralogy

Main commodities Au
Other commodities Pb; Sb; Zn
Ore minerals arsenopyrite; galena; gold; malachite; pyrite; pyrrhotite; stibnite; sphalerite
Gangue minerals quartz; siderite

Geographic location

Quadrangle map, 1:250,000-scale MM
Quadrangle map, 1:63,360-scale C-2
Latitude 63.574
Longitude -150.7421
Nearby scientific data Find additional scientific data near this location
Location and accuracy The Humboldt mine (Cobb, 1980 [OFR 80-363]) is at an elevation of about 4100 feet on the east flank of a ridge above the East Fork of Glen Creek . It is in the NE1/4 NE1/4 section 36, T. 15 S., R. 17 W., Fairbanks Meridian. The location is probably accurate within 500 feet. The mine is number 20 of Cobb (1972 [MF 366]), 56 of Bundtzen, Smith and Tosdal (1976), 61 of Bundtzen (1981), and 78 of Thornsberry, McKee, and Salisbury (1984).

Geologic setting

Geologic description

The Humboldt (also Humbolt) mine is in the Birch Creek Schist, probably a short distance west of a nearly vertical fault that strikes NE and juxtaposes Birch Creek and Spruce Creek rocks. Subunits of the Birch Creek Schist at the mine include quartz-chlorite-biotite schist, micaceous quartzite, garnet schist, and quartz-chlorite-muscovite schist (Bundtzen, 1981; Thornsberry, McKee, and Salisbury, 1984, fig. K-2 and v. 2, occurrence 78). The schistosity strikes N37W and dips 27 SW (Capps, 1919, p. 99).
The deposit consists of a series of quartz veins in a zone 22 to 50 feet wide. A short adit was driven on a nearly vertical vein about 4 feet wide that strikes N55E. The wall rocks adjoining the zone are impregnated with siderite and locally stained with malachite. The veins contain pyrite, pyrrhotite, galena, sphalerite, stibnite(?), minor arsenopyrite, and free gold (Moffit, 1933, p. 333; Bundtzen, 1981; Thornsberry, McKee, and Salisbury, 1984, v. 2, occurrence 78). A composite representative sample across about 15 feet of the mineralized zone assayed 1.02 ounces of gold per ton, 0.27 ounce of silver per ton, and 0.046 percent arsenic. A sample of limonitic gossan assayed 3.69 ounces of silver per ton, 1.45 percent lead, and 2. 10 percent zinc (Thornsberry, McKee, and Salisbury, 1984, v. 2, occurrence 78).
Geologic map unit (-150.744383990944, 63.5734983522546)
Mineral deposit model Low sulfide gold-quartz vein (Cox and Singer, 1986; model 36a).
Mineral deposit model number 36a
Age of mineralization The deposit is assumed to be Eocene (see record MM091).
Alteration of deposit Carbonate alteration of wallrocks; silicification; oxidation of iron and copper minerals.

Production and reserves

Workings or exploration The deposit was developed by a tunnel about 50 feet long and by surface cuts. The tunnel was caved by 1916 (Capps, 1919). Probably not much work has been done since then.
Indication of production Yes; small
Production notes Gold reportedly was recovered from a test shipment of several hundred pounds of selected, quartz-rich ore.

Additional comments

The Humboldt mine is in Denali National Park and Preserve.

References

MRDS Number A011225

References

Bundtzen, T.K., 1981, Geology and mineral deposits of the Kantishna Hills, Mt. McKinley quadrangle, Alaska: M. S. Thesis, University of Alaska, College, Alaska, 238 p.
Reporters C.C. Hawley
Last report date 5/3/2001