Location: This prospect is at an elevation of about 2,440 feet on the crest of a ridge east of upper Bonanza Creek. It is about 0.5 mile south-southwest of hill 2765 and about 0.3 mile east-southeast of the center of sec. 29, T. 12 N., R. 59 W., of the Seward Meridian. It is locality 2 of Frost (1990); the location is accurate.
Geology: Frost (1990) describes gold- and pyrite-bearing quartz veins cutting sericitized andesite and volcaniclastic hornfels at this site. The veins are vuggy and contain euhedral quartz prisms extending into open spaces. The other common gangue minerals in the iron-oxide stained veins are calcite and chlorite. A quartz vein at this prospect contained 20 parts per million (ppm) gold (Frost, 1990, sample locality 2). The rocks in the area include thermally metamorphosed Jurassic volcanic or volcaniclastic rocks near the contact with a small granitic stock (Box and others, 1993). The thermal metamorphism is caused by a large mid-Cretaceous granitic pluton exposed to the the north in the headwaters of the Tuluksak River. Wenz (2004, 2005) describes both high and low temperature mineralization at this prospect. Quartz-chlorite-calcite veins with magnetite, chalcopyrite, and native gold are part of the higher temperature suite. Fluid inclusions in these veins have first homogenization temperatures of 282 to 557 degrees centigrade and salinities of 17 to 57 weight percent NaCl. Samples of this mineralization contain up to 10.9 ppm gold. The lower temperature mineralization includes vuggy chalcedony-bearing veins that are known to contain up to 723 parts per billion (ppb) gold, 9.88 ppm silver, and 280 ppb mercury. Sericite-altered dikes and carbonate-replaced fault breccia are also considered part of the lower temperature mineralization. Altered fault breccia contains up to 15.1 ppm gold and 1.6 ppm mercury. In 2005, Tonogold Resources, Inc. (2006) negotiated a mining lease agreement with Calista Corporation covering the Nyac area. They completed detailed soil geochemical surveys in several areas including this prospect in the summer of 2005. Strachan (2005) shows a map of soil samples in the area of this prospect. He reported that 58 of 518 surface samples contained 0.105 to 2.86 ppm gold. Seven rock chip samples contained 0.121 to 15.1 ppm gold. In 2006, Tonogold (2007) expanded their geochemical coverage of the area considerably, did surface mapping and sampling, and cut several trenches. Some outcrop and float samples which had visible gold contained more than 1,000 ppm gold. Wenz (2004, 2005) also maps a large area of gaudy, orange-weathering altered volcanic rocks with anomalous gold values in the flat saddle between this prospect and hill 2046 to the southeast and on the hillside between that saddle and this prospect.
Workings: In 2005, Tonogold Resources, Inc. (2006) negotiated a mining lease agreement with Calista Corporation covering the Nyac area. They completed detailed soil geochemical surveys in several areas including this prospect in the summer of 2005. In 2006, they markedly expanded the soil survey around this propect, mapped the surface in the vicinity, and cut several trenches.
Age: Wenz (2004) reports Ar-Ar ages of 113 +/- 1 Ma of intrusive rocks near this prospect.
Alteration: Silicification, sericitization, and carbonate replacement.

Commodities (Major) - Au; (Minor) - Cu
Development Status: None
Deposit Model: Au-Bi-Te veins.

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Commodity List

This is a list of exploitable or exploited mineral commodities recorded at this locality.

ⓘ Copper

Mineral List

6 valid minerals.