Glenn

Prospect, Inactive

Alternative names

Glen
Swisher

Commodities and mineralogy

Main commodities Ag; Au
Other commodities Pb; Sb; Zn
Ore minerals arsenopyrite; boulangerite; galena; goethite; jamesonite; jarosite; pyrite; scorodite; sphalerite; stibiconite; stibnite; tetrahedrite
Gangue minerals potassium feldspar; quartz

Geographic location

Quadrangle map, 1:250,000-scale MM
Quadrangle map, 1:63,360-scale C-2
Latitude 63.5658
Longitude -150.785
Nearby scientific data Find additional scientific data near this location
Location and accuracy
The Glenn (sometimes called Glen or Swisher) prospect (Cobb, 1980 [OFR 80-363]) is at altitude of about 4200 feet on the south side of Glacier Peak, within 1000 feet of hilltop 4310. It is near the middle of the S1/2 SE1/4 of section 35, T. 15 S., R. 17 W., Fairbanks Meridian. The location is accurate within 500 feet.
The prospect is location 17 of Cobb (1972 [MF 366]), and is included in location 13 of MacKevett and Holloway (1977). It corresponds to number 47 of Bundtzen, Smith, and Tosdal (1976), 216 of Hawley and Associates (1978), 52 of Bundtzen (1981), and 70 of Thornsberry, McKee, and Salisbury (1984).

Geologic setting

Geologic description

The country rock at the Glenn prospect is micaceous quartz schist of the upper Precambrian Birch Creek Schist, near the rest of the Kantishna antiform (MM091) (Bundtzen, 1981). The schist strikes north and dips 20-40 W. The prospect is about 500 feet north of a fault that strikes WNW and juxtaposes Spruce Creek lithologies (to the south) against Birch Creek Schist (Thornsberry, McKee, and Salisbury, 1984, fig. K-2).
The deposit is a sulfide-bearing quartz vein that locally contains potassium feldspar. The vein is 4 to 10 feet thick, strikes N80W and is nearly vertical. The ore minerals include arsenopyrite, galena, boulangerite, jamesonite, stibnite, sphalerite, and, tentatively, tetrahedrite; free gold occurs locally (Capps, 1919, p. 100; Bundtzen, 1981; Thornsberry, McKee, and Salisbury, 1984). The sulfides are partly oxidized to scorodite, stibiconite, goethite, and jarosite.
The vein was explored by two adits. A sample from the upper dump assayed 8.54 ounces of silver per ton, 0.03 ounce of gold per ton, 0.086 percent copper, 3.4 percent lead, 0.480 percent zinc, 2.05 percent antimony, and 2.05 percent arsenic. Ore from the lower dump assayed 23.08 ounces of silver per ton, 0.05 ounce of gold per ton, 0.093 percent copper, 6.55 percent lead, 1.00 percent zinc, and less than 1 percent each of arsenic and antimony.
Geologic map unit (-150.787284344459, 63.5652973722185)
Mineral deposit model Polymetallic vein (Cox and Singer, 1986; model 22c).
Mineral deposit model number 22c
Age of mineralization The deposit is assumed to be Eocene (see record MM091).
Alteration of deposit Silicification and introduction of potassium feldspar. Oxidation of iron, arsenic, and antimony minerals.

Production and reserves

Workings or exploration The Glenn prospect was explored between 1906 and 1909 by a group led by Tom Lloyd, an early local landowner. The exploration consisted chiefly of two adits. The portal of the lower tunnel is at an elevation of about 4050 feet; the upper portal is at about 4250 feet (Wells, 1933, p. 373). The tunnels were caved when Capps (1919) visited the property in 1916. By 1931, the property was controlled by Lee Swisher, but no more underground work was done (Wells, 1933). Bundtzen, Smith, and Tosdal (1976), Hawley and Associates (1978), and Thornsberry, McKee, and Salisbury (1984) mapped the site or collected rock and soil samples.
Indication of production Undetermined

Additional comments

The prospect is in Denali National Park and Preserve.

References

MRDS Number A011217

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 5/2/2001