Gable Mountain Occurrence, Glacier Bay District, Juneau District, Skagway-Hoonah-Angoon Borough, Alaska, USA

The deposit is within Glacier Bay National Park and Preserve where exploration and development is restricted.
Location: This occurrence is in Glacier Bay National Park and Preserve at an elevation of about 4,500 feet; it is on a rugged ridge about 0.6 miles southeast of the summit of Gable Mountain. It is in west-central part of section 29, T. 32 S., R. 53 E. of the Copper River Meridian. This location corresponds to number 75 on Plate 3 of Brew and others (1978). Location 14 on Plate 1 of MacKevett and others (1971) and location 4 of Cobb (1972; MF-424) appear to refer to the same occurrence but are shown approximately 1 mile to the northwest of the summit of Gable Mountain. Because of the discrepancies between different authors regarding the location of this occurrence, it should probably be considered accurate only to within about 1 mile.
Geology: The following description is summarized from Brew and others (1978). At site 1 at an elevation of 4,475 feet, there is a 0.7-foot-wide shear zone which has quartz stringers and copper stains. Below the shear zone there is quartz diorite float that has joint coatings of malachite and chrysocolla. Joint coatings of iron sulfide are reported in quartz diorite at a second site 8,000 - 9,000 feet to the southeast (but the plotted location is about 3,000 - 4,000 feet to the southwest). At site 1, a composite grab sample contained 1,000 ppm copper; a channel sample across the 0.7-foot-wide shear zone contained 250 ppm copper and 7 ppm silver. At Site 2, 7 grab samples contained up to 970 ppm copper, 3 ppm silver, 200 ppm molybdenum, and 150 ppm tungsten. Based on the Cretaceous age of the intrusion (Brew and others, 1978), the mineralization must be Cretaceous or younger in age.
Age: The deposit must be Cretaceous or younger in age based on the Cretaceous age of the intrusion that hosts it (Brew and others, 1978).

Commodities (Major) - Ag, Cu; (Minor) - Mo, W
Development Status: None
Deposit Model: There is too little information to assign a model type.

References:
Berg, H.C., 1984, Regional geologic summary, metallogenesis, and mineral resources of southeastern Alaska: U.S. Geological Survey Open-file Report 84-572, 298 p., 1 plate, scale 1:600,000. Brew, D.A., Johnson, B.R., Grybeck, D., Griscom, A., Barnes, D.F., Kimball, A.L., Still, J.C., and Rataj, J.L., 1978, Mineral resources of the Glacier Bay National Monument Wilderness Study Area, Alaska: U.S. Geological Survey Open-File Report 78-494, 670 p., 7 sheets. Cobb, E.H., 1972, Metallic mineral resources map of the Skagway quadrangle, Alaska: U.S. Geological Survey Miscellaneous Field Studies Map MF-424, 1 sheet, scale 1:250,000. Cobb, E.H., 1978, Summary of references to mineral occurrences (other than mineral fuels and construction materials) in the Mt. Fairweather and Skagway quadrangles, Alaska: U.S. Geological Survey Open-File Report 78-316, 123 p. Cobb, E.H., 1981, Summaries of data on and lists of references to metallic and selected nonmetallic mineral occurrences in the Skagway quadrangle, Alaska; Supplement to Open-File Report 78-316; Part A, Summaries of data to January 1, 1980: U.S. Geological Survey Open-File Report 81-82-A, 11 p. MacKevett, E.M., Jr., Brew, D.A., Hawley, C.C., Huff, L.C., and Smith, J.G., 1967, Mineral resources of Glacier Bay National Monument, Alaska: U. S. Geological Survey Open-File Report 151, 176 p. MacKevett, E.M., Jr., Brew, D.A., Hawley, C.C., Huff, L.C., and Smith, J.G., 1971, Mineral resources of Glacier Bay National Monument, Alaska: U.S. Geological Survey Professional Paper 632, 90 p., 12 plates, scale 1:250,000.