Cathedral Prospect, Hyder District, Prince of Wales-Outer Ketchikan Borough, Alaska, USA
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Location: The Cathedral prospect is in Section 25 at an elevation of about 3100-3400 feet on the south end of the bold ridge between Chickamin and West Texas glaciers, just above west-facing cliffs (Berg and others, 1977, p. 90; Elliott and Koch, 1981, p. 11, loc. 25). The location is accurate to within about a quarter of a mile.
Geology: The country rocks in the area of the Cathedral prospect include pelitic metasedimentary strata of the Jurassic or older Mesozic Hazelton Group; the Triassic Texas Creek Granodiorite, which underlies and locally intrudes the Hazelton; and the Eocene Hyder Quartz Monzonite, which intrudes the Hazelton and Texas Creek rocks (Berg and others, 1977, p. 15-18, 22-23; Smith, 1977; Koch, 1996). The deposit (Berg and others, 1977, p. 38-39, 90-91; Elliott and Koch, p. 11, loc. 25) consists of quartz fissure veins up to about 5 feet thick in graywacke hornfels. The veins contain shoots of nearly massive sphalerite and (or) galena, together with subordinate amounts of chalcopyrite, pyrite, and pyrrhotite. Channel samples collected in 1972 by the U. S. Bureau of Mines across the full width of the thickest (5-foot) vein and its 7-inch-thick footwall massive sulfide zone averaged 70 ppm Ag, 0.17% Cu, 0.75% Pb, and 7.5% Zn. A channel sample only of the massive sulfide contained 4.4 oz Ag per ton, 0.27% Cu, 0.9% Pb, and 35% Zn. One analysis showed 0.05 ppm Au. Samples of a smaller (2.5-inch-thick) sulfide-bearing vein assayed 20 oz Ag per ton, 19% Pb, and 9% Zn.
Workings: Early workings included an approximately 10-foot-long stripped area. Channel samples collected in 1972 by the U. S. Bureau of Mines across the full width of the thickest (5-foot) vein and its 7-inch-thick footwall massive sulfide zone averaged 70 ppm Ag, 0.17% Cu, 0.75% Pb, and 7.5% Zn. A channel sample only of the massive sulfide contained 4.4 oz Ag per ton, 0.27% Cu, 0.9% Pb, and 35% Zn. One analysis showed 0.05 ppm Au. Samples of a smaller (2.5-inch-thick) sulfide-bearing vein assayed 20 oz Ag per ton, 19% Pb, and 9% Zn.
Alteration: Locally intense iron staining.
Commodities (Major) - Ag, Au, Cu, Pb, Zn
Development Status: None
Deposit Model: Polymetallic veins
6 entries listed. 6 valid minerals.
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Berg, H.C., Elliott, R.L., Smith, J.G., Pittman, T.L., and Kimball, A. L., 1977, Mineral resources of the Granite Fiords Wilderness Study Area, Alaska, with a section on aeromagnetic data by Andrew Griscom: U.S. Geological Survey Bulletin 1403, 151 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. 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.