Pfaff; Battle Lake Prospect, Bristol Bay District, Lake and Peninsula Borough, Alaska, USA
Detterman and Reed (1980, p. B79) suggested that: 'This area of Tertiary volcanic and intrusive rocks warrants further prospecting and geochemical sampling for precious and base-metal deposits.' Such work is unlikely in the near term, however, because the prospect is in Katmai National Park.
Location: The Pfaff (Battle Lake) prospect is at an elevation of about 2,600 feet about 3.5 miles due east of the north end of Battle Lake. It is in the NW1/4 SW1/4 sec. 29, T. 12 S., R. 33 W., Seward Meridian. The location is accurate within about 0.5 mile. The prospect is number 18 of Detterman and Cobb (1972) and number 16 of Detterman and Reed (1980, fig. 6). The prospect is in Katmai National Park.
Geology: The country rocks at this prospect are Tertiary dacite and interbedded tuff and volcanic breccia (Detterman and Reed, 1980). About 0.5 mile northwest of the prospect, the dacite and fragmental units are overlain by Tertiary andesite and basalt. The deposit consists of north-striking, quartz-sulfide veins that cut propylitically-altered flows, tuff, and breccia (Detterman and Reed, 1980). The veins range from a few inches to more than 6 feet thick, and can be traced through outcrops and pits for about 1,000 feet. Locally, the veins comprise quartz-cemented breccia of intensely altered andesite or dacite; the quartz is vuggy and some of the cavities are lined with amethyst crystals (C. C. Hawley, examination notes and samples, 1986). The veins locally contain abundant chalcopyrite, pyrite, and an unidentified silver-bearing sulfosalt; some copper-rich parts of the veins contain abundant disseminated free gold (collection of prospector Ray Gatz, circa 1970). Hawley tentatively identified bornite during his site visit in 1986. Sulfide-rich veins are locally oxidized to malachite and chrysocolla(?). Selected samples collected by Detterman and Reed (1980) contained 0.41 to 36.4 ounces of gold per ton and 6.6 to 168.8 ounces of silver per ton. Copper content ranged from almost nil in quartz-rich veins to several percent in sulfide-rich veins. The property was drilled by its owners in 1965; according to Detterman and Reed (1980), results of the drilling were not encouraging.
Workings: The property was discovered by Ernie Pfaff in about 1964, and the owners of the claims drilled a few diamond core holes in 1965. Pfaff continued to prospect with cuts and trenches until about 1980. Essentially no work was done after the prospect area was included in Katmai National Park, and the claims were allowed to lapse after Pfaff's death.
Alteration: Propylitically-altered volcanic breccia and dacitic flows; silicification; local argillic alteration. Oxidation of copper.
Production: High-grade specimens of gold ore were collected at the site and some, such as those in the collection owned by prospector Ray Gatz, may have been sold.
Commodities (Major) - Ag, Au; (Minor) - Cu
Development Status: None
Deposit Model: Creede-type epithermal vein (Cox and Singer, 1986, model 25b).
ReferencesCobb, E.H., 1976, Summary of references to mineral occurrences (other than mineral fuels and construction materials) in the Iliamna, Lake Clark, Lime Hills, and McGrath quadrangles, Alaska: U.S. Geological Survey Open-File Report 76-485, 101 p. Detterman, R.L., and Cobb, E.H., 1972, Metallic mineral resources map of the Iliamna quadrangle, Alaska: U.S. Geological Survey Miscellaneous Field Studies Map MF-364, 1 sheet, scale 1:250,000. Detterman, R.L., and Reed, B.L., 1980, Stratigraphy, structure, and economic geology of the Iliamna quadrangle, Alaska: U.S. Geological Survey Bulletin 1368-B, 86 p.
| Bornite ?|
8 entries listed. 7 valid minerals.
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Locality Updated: Reyran valley, Fréjus, Var, Provence-Alpes-Côte d'Azur, FranceFrom Pascal Chollet, 10th Dec 2013 18:26:20