Friday the 13th Pup Occurrence, Koyukuk Mining District, Yukon-Koyukuk Census Area, Alaska, USAi

Regional Level Types
Friday the 13th Pup Occurrence	Occurrence
Koyukuk Mining District	Mining District
Yukon-Koyukuk Census Area	Census Area
Alaska	State
USA	Country

Location: 'Friday the 13th Pup' creek is not show on the topographic map but it is a short, northwest tributary to Right Fork Creek; its mouth is about 0.5 mile upstream from the mouth of Right Fork Creek. The occurrence is at an elevation of about 1,900 feet on the northwest side of Right Fork, about 0.3 mile southeast of the center of section 14, T. 31 N., R 12 W., of the Fairbanks Meridian. The location is accurate.
Geology: This occurrence consists of randomly-spaced veins and veinlets in phyllite exposed in bluff faces (Kurtak and others, 1999). Eighteen veins occur in one 100-foot-wide exposure of the phyllite. The veins average about 0.5 inches in width; they generally strike about N60W and dip 75SW. The veins appear to fill a fracture set that cuts the phyllite. They consist of coarse, white quartz, calcite, ankerite and dolomite, 1-2% pyrite, and traces of arsenopyrite, stibnite, and pyrrhotite. Visible gold occurs in these veins, mostly along their margins. A sample of a vein containing visible gold contains 17.8 ppm gold(Kurtak and others, 1999). Several other veins contain 415 ppb to 63.56 ppm gold, 126 to 3,802 ppm arsenic, and 7 to 748 ppm antimony. Samples of phyllitic with minor pyrite in the vicinity of the veins contain 13 to 38 ppb Au. Eden (2000) also identified traces of marcasite, chalcopyrite, hematite, sphalerite, galena, and rutile in the veins. The rocks in the vicinity are upper Devonian phyllite and mica schist (Eden, 2000).
Workings: Surface sampling and geologic mapping.
Alteration: The wallrock apparently is not altered.

Commodities (Major) - Au; (Minor) - As, Sb
Development Status: None
Deposit Model: Low-sulfide Au-quartz vein (Cox and Singer, 1986; model 36a)

Other Databases

Link to USGS - Alaska:	WI032

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References