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REC 3-9

Occurrence, Inactive

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Commodities and mineralogy

Main commodities Argillite
Ore minerals clay
Gangue minerals quartz

Geographic location

Quadrangle map, 1:250,000-scale SR
Quadrangle map, 1:63,360-scale B-7
Latitude 60.4377
Longitude -149.3732
Nearby scientific data Find additional scientific data near this location
Location and accuracy The occurrence is located in the road cut along the Seward Highway north of the bridge at the south end of Lower Trail Lake. It is in the center of section 13, T. 4 N., R. 1 W., of the Seward Meridian. This is location S-232 of Jansons and others (1984). This location is accurate to within a quarter of a mile.

Geologic setting

Geologic description

This occurrence consists of argillite that is exposed along a road cut near the bridge across Trail River. Both the bedding and cleavage in the deposit strike north to N15E and dip 55SE (Eckhart and Plafker, 1959). The deposit is exposed along strike for 1,750 feet and for a vertical distance of 100 feet. In thin section, the rock consists of 25 percent to 50 percent silt-size particles embedded in a dark-colored matrix of clay-sized particles. Clear angular fragments of quartz and plagioclase along with white mica and chlorite comprise the rest of the rock. Accessory minerals are abundant magnetite, and scant epidote, garnet, tourmaline, carbonate, and zircon (Eckhart and Plafker, 1959). Nelson and others (1985) mapped this area as undivided sedimentary rock of the Valdez Group of Late Cretaceous age.
Geologic map unit (-149.375332090512, 60.4371237661297)
Age of mineralization Cretaceous or younger; the argillite is in rocks of the Valdez Group of Late Cretaceous age.

Production and reserves

Workings or exploration There are no workings or improvements reported in the literature. The occurrence was sampled in 1953 and exhibits favorable bloating characteristics at 2,200 -2,300 degrees F (Eckhart and Plafker, 1959). It would be suitable for haydite.
Indication of production None
Reserve estimates The U.S. Bureau of Mines estimated a reserve of 50 million tons (Jansons and others, 1984).

References

References

Eckhart, R. A., and Plafker, G., 1959, Haydite raw material in the Kings River, Sutton, and Lawing areas, Alaska: U.S. Geological Survey Bulletin 1039-C, p. 33-65.
Hoekzema, R.P., and Sherman, G.E., 1983, Mineral investigations in the Chugach National Forest, Alaska (Peninsula study area): U.S. Bureau of Mines in-house report; held at U.S. Bureau of Land Management Alaska State Office, Anchorage, 524 p.
Jansons, Uldis, Hoekzema, R.B., Kurtak, J.M., and Fechner, S.A., 1984, Mineral occurrences in the Chugach National Forest, southcentral Alaska: U.S. Bureau of Mines Mineral Land Assessment 5-84, 218 p., 2 sheets, scale 1:250,000.
Nelson, S.W., Dumoulin, J. A., and Miller, M.L., 1985, Geologic map of the Chugach National Forest, Alaska: U.S. Geological Survey Miscellaneous Field Studies Map MF-1645-B, 16 p., 1 sheet, scale 1:250,000.
Reporters Jeff A. Huber and Carol S. Huber (Anchorage)
Last report date 7/13/2000