Unnamed (near Cone Mountain)

Prospect, Probably inactive

Commodities and mineralogy

Main commodities U
Other commodities Ce; La; Mo; Nd; Th
Ore minerals unspecified radioactive minerals

Geographic location

Quadrangle map, 1:250,000-scale BC
Quadrangle map, 1:63,360-scale C-6
Latitude 56.514
Longitude -131.735
Nearby scientific data Find additional scientific data near this location
Location and accuracy This prospect is about 1.0 mile south-southwest of Cone Mountain; it is at an elevation of about 3,000 feet near the northeast corner of T. 62 S., R. 88 E., of the Copper River Meridian. The location is probably accurate within about a quarter of a mile.

Geologic setting

Geologic description

The country rocks in the general area of the Cone Mountain prospect are a Miocene (?) alkali feldspar granite stock and associated quartz-porphyritic rhyolite dikes (Koch, 1996, 1997). The prospect is on the western margin of the stock, which intrudes Eocene granodiorite and quartz monzonite plutons and Mesozoic or Paleozoic pelitic schist and paragneiss. A group of 145 claims was staked in 1976, presumably for uranium-bearing and related minerals (Elliott and Koch, 1981, loc. 4; Koch and others, 1981; U. S. Geological Survey, 1979). Geochemical surveys [(Koch and Elliott, 1981 (OFR 81-728C-K)] show high values of silver, beryllium, molybdenum, niobium, lead, tin, yttrium, rare earth elements, and zinc in rock, stream-sediment and heavy-mineral concentrate samples from the immediate area of the stock. Differentiation enrichment of these elements in such a highly-evolved silicic magma may account for most of the values reported, but a few high lead and zinc values suggest local sulfide deposition.
In 1976, Pacific Coastal Minerals staked 176 claims in the area; they held them several years and did some drilling. Still and others (2002) collected samples of granite at two localities between Cone Mountain and Black Crag; they contained up to 140 parts per million (ppm) cerium, 75 ppm lanthanum, 48 ppm neodymium, and 66.9 ppm thorium. They also collected 8 samples of a variety of felsic volcanic and intrusive rocks. The highest values were in a sample of molybdenite-bearing rhyolite breccia that contained 1,740 ppm cerium, 954 ppm lanthanum, 440 ppm neodymium, 60 ppm samarium, 72.6 ppm thorium, and 2,098 ppm molybdenum.
Geologic map unit (-131.736690296161, 56.5136698746207)
Mineral deposit model Felsic plutonic uranium?
Age of mineralization Miocene?

Production and reserves

Workings or exploration In 1976, Pacific Coastal Minerals staked 176 claims in the area; they held them several years and did some drilling.
Indication of production None


MRDS Number A010211


Still, J.C., Bittenbender, P.E., Bean, K.W., and Gensler, E.G., 2002, Mineral assessment of the Stikine area, central southeast Alaska: Bureau of Land Management Technical Report 51, 560 p.
Reporters H. C. Berg (Fullerton, California); D.J. Grybeck (Port Ludlow, WA)
Last report date 3/4/2008