Ninety-six; Gold Eagle Prospect, Hyder District, Prince of Wales-Outer Ketchikan Borough, Alaska, USA
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Location: This prospect is in Section 23 at an elevation of about 500 feet at the west base of Mineral Hill and just off the old road on the east bank of Texas Creek (Elliott and Koch, 1981, p. 15, loc. 59). The location is probably accurate within a tenth of a mile. Also see Additional Comments field, below.
Geology: The country rocks in the area of this prospect are the Triassic Texas Creek Granodiorite, which underlies and locally intrudes pelitic metasedimentary and subordinate andesitic metavolcanic strata of the Jurassic or older Mesozoic Hazelton Group; the Eocene Boundary Granodiorite, which intrudes the Hazelton and Texas Creek rocks; and still-younger Tertiary lamprophyre dikes, which cut all the other rocks (Smith, 1973, 1977; Koch, 1996). The deposit (Buddington, 1925, p. 87, and 1929, p. 93; summarized by Cobb, 1978, p. 61) is in a breccia zone in a Texas Creek granodiorite dike in interbedded slate and quartzite. The breccia zone is about 5 feet thick and was traced in outcrop for about 200 feet. The zone consists of reticulating quartz stringers and veinlets that aggregate 12-14 inches in thickness that contain galena, sphalerite, a little chalcopyrite, and sparse tetrahedrite. A 63-foot adit was driven to intersect the lode, but there is no record of any production. Maas and others (1995, p. 254) suggest that the age of the Ninety-six (96) prospect is Eocene, based on similarities in mineralogy, structural setting, and hostrock, to isotope-dated Eocene deposits in the Hyder district (see, for example, BC086). If so, the deposit is contemporaneous with emplacement of the Boundary Granodiorite.
Workings: Deposit was explored in the 1920's by opencuts and a 100-foot adit that was driven to intersect the lode.
Age: Maas and others (1995, p. 254) suggest that the age of the Ninety-six (96) prospect is Eocene, based on similarities in mineralogy, structural setting, and hostrock, to isotope-dated Eocene deposits in the Hyder district (see, for example, BC086). If so, the deposit is contemporaneous with emplacement of the Boundary Granodiorite.
Alteration: Hostrock identified as quartzite may indicate silicification of pelitic country rock.
Production: Reported small test shipment of hand-cobbed ore (Maas and others, 1995, p. 258).
Commodities (Major) - Cu, Pb, Zn
Development Status: Yes; small
Deposit Model: Polymetallic veins
5 entries listed. 5 valid minerals.
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Buddington, A.F., 1925, Mineral investigations in southeastern Alaska: U.S. Geological Survey Bulletin 773-B, p. 71-139. Buddington, A.F., 1929, Geology of Hyder and vicinity, southeastern Alaska, with a reconnaissance of Chickamin River: U.S. Geological Survey Bulletin 807, 124 p. Cobb, E.H., 1978, Summary of references to mineral occurrences (other than mineral fuels and construction materials) in the Bradfield Canal quadrangle, Alaska: U.S. Geological Survey Open-File Report 78-922, 98 p. Elliott, R.L., and Koch, R.D., 1981, Mines, prospects, and selected metalliferous mineral occurrences in the Bradfield Canal quadrangle, Alaska: U.S. Geological Survey Open-File Report 81-728-B, 23 p., 1 sheet, scales 1:250,000 and 1:63,360. Koch, R.D., 1996 [In press), Reconnaissance geologic map of the Bradfield Canal quadrangle, southeastern Alaska: U.S. Geological Survey Open-File Report, 1 sheet, scale 1:250,000. Maas, K.M., Bittenbender, P E., and Still, J.C., 1995, Mineral investigations in the Ketchikan mining district, southeastern Alaska: U.S. Bureau of Mines Open-File Report 11-95, 606 p. Smith, J.G., 1973, A Tertiary lamprophyre dike province in southeastern Alaska: Canadian Journal of Earth Sciences, v. 10, p. 408-420. Smith, J.G., 1977, Geology of the Ketchikan D-1 and Bradfield Canal A-1 quadrangles, Alaska: U.S. Geological Survey Bulletin 1425, 49 p., 1 plate. U.S. Bureau of Mines, 1979, Claim map 118: Mines and prospects of the Bradfield Canal quadrangle, Alaska: U.S. Bureau of Mines Open-File Report 20-73, 1 sheet, scale 1:250,000.