Prospect, Inactive

Commodities and mineralogy

Main commodities Cu; Zn
Other commodities Ag; Pb
Ore minerals azurite; chalcopyrite; galena; magnetite; malachite; pyrite; smithsonite; sphalerite
Gangue minerals quartz

Geographic location

Quadrangle map, 1:250,000-scale DN
Quadrangle map, 1:63,360-scale C-2
Latitude 63.5565
Longitude -150.7426
Nearby scientific data Find additional scientific data near this location
Location and accuracy
The Lloyd prospect (Cobb, 1980 [OFR 80-363]) is in the canyon of the East Fork of Glen Creek, about 1500 feet due north of the confluence of the East and West forks of Glen Creek. The location is accurate within 500 feet.
The prospect corresponds to number 21 of Cobb (1972 [MF 366]), 52 of Bundtzen, Smith, and Tosdal (1976), 56 of Bundtzen (1981), 239 of Hawley and Associates (1978), and 77 of Thornsberry, McKee, and Salisbury (1984).

Geologic setting

Geologic description

The country rocks in the area of the Lloyd prospect are metachert (quartzite?) and garnet-quartz-muscovite schist of the upper Precambrian Birch Creek Schist (Bundtzen, 1981). The strata dip gently north and form asymmetric recumbent folds that plunge about S 80 W at a low angle (Thornsberry, McKee, and Salisbury, 1984, v. 2, occurrence 77).
The deposit consists of stratiform sulfide minerals concentrated in bands up to about 1/2 inch thick in a metachert layer as much as 3 feet thick. The sulfide-rich layers appear to thicken in fold crests. Sphalerite is the most abundant metallic mineral. It is accompanied by pyrite and lesser amounts of chalcopyrite, galena, and magnetite (Bundtzen, 1981). Outcrops are coated with azurite, malachite, and smithsonite. A 5-foot channel sample of a section thickened by folding assayed about 0.15 ounce of silver per ton, 2.2 percent zinc, 0.355 percent copper, and 0.07 percent lead. A selected sample of the richest material on the dump assayed 0.85 ounce of silver per ton, 5.6 percent zinc, 1.1 percent copper, and 0.215 percent lead (Thornsberry, McKee, and Salisbury, 1984, v. 2, occurrence 77). Bundtzen (1981) reported that another selected sample assayed 0.01 ounce of gold per ton.
This stratabound deposit predates recumbent folding of the Birch Creek Schist. It appears to be a zinc-rich, syngenetic, volcanogenic deposit of late Precambrian age.
Geologic map unit (, )
Mineral deposit model Stratabound base-metal sulfide deposit, possibly of exhalative origin.
Age of mineralization Possibly late Precambrian, the protolith age of the Birch Creek Schist.
Alteration of deposit Oxidation of copper and zinc minerals.

Production and reserves

Workings or exploration The Lloyd prospect explored by a 24-foot-long tunnel before 1916 (Capps, 1919). Very little work has been done since then.
Indication of production None

Additional comments

The prospect is in Denali National Park and Preserve.