Similar to Tin Creek-Midway (MG043), and Rat Fork-Headwall (MG059) prospects. The Badnews skarn prospect contains more gold than any other prospect or occurrence in the Farewell Mineral Belt.
Location: The Badnews Prospect is located on a steep and precipitous, north-facing slope of Peak 6,920, at an elevation of 5,700 feet (1,738 m) in the SW1/4 sec. 32, T. 26 N., R. 24 W., of the Seward Meridian. The location is from Foley (1987).
Geology: The Badnews polymetallic prospect is a Cu-Pb-Zn-Ag-Au (Co-Pb) skarn deposit in tightly folded limestone, siltstone, and argillite of the mid-Silurian Terra Cotta Mountains Sandstone, a unit of the Dillinger subterrane (Bundtzen, Harris, and Gilbert, 1997). The limestone layers have been preferentially replaced by skarn minerals and locally sulfides; clastic rocks have been transformed into purple-green hornfels. Central to the prospect area is a granodiorite porphyry stock with apophyses and numerous dikes intruding a large aureole of hornfelsed sedimentary rocks (Bundtzen, Harris, and Gilbert, 1997). Several east-west trending, high-angle, granodiorite dikes cut the limestone; the dikes are apparently pathways for hydrothermal-skarn mineralization. A post skarn breccia occurs at the contact of one granodiorite dike. Principle sulfide minerals include; chalcopyrite, pyrrhotite, sphalerite, and a trace of galena. Pyrrhotite is the dominant sulfide in practically all mineralized skarn zones. Skarn gangue includes abundant recrystallized calcite and red garnet, with minor epidote and quartz. Massive sulfide pods and mantos ranging up to 10 meters thick can be traced laterally for several hundred meters (Brewer and others, 1992). Individual sulfide zones reach a maximum thickness of 0.7 meters within skarn zones up to 2 meters wide. Sphalerite is most abundant in epidote-garnet-rich rock whereas chalcopyrite and pyrrhotite are most abundant in lighter calcite-garnet rock (Foley, 1987). In sulfide skarns where chalcopyrite and sphalerite dominate, 23 grab samples averaged 3.7 percent zinc and 0.4 percent copper (Brewer and others, 1992). Selected samples from zinc-rich areas also contain up to 1,740 ppm cadmium. Overall gold values are more anomalous in the Badnews skarn prospect than in any other area of the Farewell Mineral Belt, with assays of up to 11.2 grams/tonne gold and 143.1 grams/tonne silver noted (Brewer and others, 1992). An average gold value of 490 ppb gold was obtained from numerous other sulfide-bearing grab samples at the prospect. Two grab samples of sulfide-bearing skarn collected by Foley (1987) contained maximum values of 9.20 percent zinc, 93 ppm lead, 0.44 percent copper, 290 ppm cobalt, and 16.6 grams/tonne silver.
Workings: The Badnews polymetallic prospect was named by Roger Burleigh during mineral investigations conducted in 1979 by Placid Oil Company. Only surface sampling has taken place at the site, mainly by Anaconda Minerals and the U.S. Bureau of Mines. Where sphalerite and chalcopyrite dominate, 23 grab samples average 3.7 percent zinc and 0.4 percent copper (Brewer and others, 1992). Overall gold values are more anomalous in the Badnews skarn prospect than in any other area of the Farewell mineral belt; with assays of up to 11.2 grams/tonne gold and 143.1 grams/tonne silver noted (Brewer and others, 1992). Two samples of sulfide-bearing skarn collected by Foley (1987) contained up to 9.20 percent zinc, 93 ppm lead, 0.44 percent copper, 290 ppm cobalt, and 16.6 grams/tonne silver.
Alteration: Strong secondary biotite (potassic) alteration in skarn.
Reserves: None.

Commodities (Major) - Ag, Au, Cu, Zn; (Minor) - Cd, Co, Pb
Development Status: No
Deposit Model: Low temperature lead-zinc skarn (Cox and Singer, 1986; model 18c).

Select Mineral List Type

Standard Detailed Gallery Strunz Chemical Elements

Commodity List

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

Mineral List

8 valid minerals.