Silver Shield

Prospect, Inactive

Commodities and mineralogy

Main commodities Ag; Pb
Other commodities Au; Ba; Cu
Ore minerals barite; cerussite; galena; limonite; pyrite; tetrahedrite
Gangue minerals calcite; quartz

Geographic location

Quadrangle map, 1:250,000-scale GU
Quadrangle map, 1:63,360-scale D-1
Latitude 62.751
Longitude -144.031
Nearby scientific data Find additional scientific data near this location
Location and accuracy The Silver Shield prospect (Cobb, 1979, p. 25) is about 1.2 mile east of the junction of Ahtell and Flat Creeks at an elevation of about 3,300 feet. The prospect is locality 14 of Richter and Matson (1972), and number 13 of MacKevett and Holloway (1977). The location is accurate to 500 feet. It is about on the center of the east side of the NE1/4, section 11, T. 11 N., R. 7 E., Copper River Meridian.

Geologic setting

Geologic description

The Silver Shield prospect is in a vertical fault zone that separates mixed sedimentary-volcanic rocks to the north and volcanic rocks to the south. The fault strikes N55E. The rocks are mapped as Pennsylvanian to Permian, Tetelna Formation by Richter (1964; 1966).
The vein was discovered by the Alaska Division of Mines and Minerals in 1963 (Richter, 1964) It is poorly exposed but appears to be a limonite-stained quartz vein about five-feet thick with local concentrations of coarse galena, that cuts locally pyritic, sedimentary and volcanic rock. A 3-foot channel sample of the vein contained a trace of gold, 19.8 ounces of silver per ton, and 1.6 percent lead. Another sample contained 21 ounces of silver per ton, and 2.4 percent lead.
Subsequent private exploration determined that the quartz occurs as veins and pods in a 35-foot vertical, fault zone. The quartz veins locally contain segregations of massive barite and lesser amounts of calcite. Galena is disseminated in crystals as much an inch across; cerussite, presumably after galena, also occurs in the veins. Some of the quartz was vuggy and argentiferous tetrahedrite occurs locally in the vuggy zones. Selected samples of tetrahedrite-rich vein material contain as much as 400 ounces of silver per ton (Richter, 1966).
Geologic map unit (-144.033186021561, 62.7506093234707)
Mineral deposit model Polymetallic vein (Cox and Singer, 1986; model 22c)
Mineral deposit model number 22c
Age of mineralization Emplaced subseqent to or is related to the border phase of the Pennsylvanian to Permian, Ahtell pluton.

Production and reserves

Workings or exploration The deposit was discovered in 1963 by the Alaska Division of Mines and Minerals and was announced in 1964. It was staked soon afterwards. The deposit has been explored by open cuts.
Indication of production None