Occurrence, Inactive

Commodities and mineralogy

Main commodities Ag; Sn; Zn
Other commodities Au; Hg; W
Ore minerals unspecified sulfide minerals
Gangue minerals axinite; quartz; tourmaline

Geographic location

Quadrangle map, 1:250,000-scale SM
Quadrangle map, 1:63,360-scale D-7
Latitude 61.77541
Longitude -158.43344
Nearby scientific data Find additional scientific data near this location
Location and accuracy The Jungjik prospect is about 0.4 mile northeast of hill 2870 on a northeast-trending, gently sloping ridgetop, in the northeast part of the Horn Mountains. The occurrence is at an elevation of about 2,700 feet in the SE1/4 sec. 36, T. 20 N., R. 51 W., of the Seward Meridian. The location is accurate.

Geologic setting

Geologic description

The Jungjik prospect consists of N25W-trending, tourmaline-axinite-quartz-sulfide breccia in andesite of the Horn Mountains volcanic field. The breccia is composed of angular fragments of altered intrusive rock nested in a matrix of black tourmaline, axinite, and disseminated gray sulfides. The breccia contains up to 20 percent black tourmaline, about 4 percent purple axinite, and 1 to 2 percent sulfides; the breccia is often altered to a ferricrete box work.
This boron-enriched breccia occurs in roof pendants above granodiorite porphyry of the Horn Mountains pluton (Bundtzen and others, 1998). The breccia averages about 10 feet thick and can be traced across the top of the ridge for about 100 feet. Four grab samples taken along 60 feet of the mineralized zone contained up to 8 parts per billion (ppb) gold, 800 ppb silver, 369 parts per million (ppm) zinc, 40 ppm tin, and 2.055 ppm mercury (Bundtzen and others, 1998).
The Jungjik prospect is in an area with anomalous stream sediment and panned concentrate samples (Gray and others, 1994; Theodorakos and others, 1992). Stream sediment samples contained up to 26 ppb gold, 950 ppb silver, 290 ppm arsenic, 57 ppm antimony, 4.0 ppm mercury, 6.4 ppm bismuth, and 0.6 ppm tellurium. Pan concentrate samples contained up to 30 ppm gold, 5 ppm silver, 1,500 ppm bismuth, 500 ppm lead, 200 ppm antimony, 1,000 ppm tungsten, and 1,000 ppm boron. Pan concentrates also contained up to 1.0 percent scheelite.
Geologic map unit (-158.435822371122, 61.7747059935614)
Mineral deposit model Sn-polymetallic veins and greisen (Cox and Singer, 1986; model 20b).
Mineral deposit model number 20b
Age of mineralization Undated; may be related to the nearby Horn Mountain pluton which has been dated at 68-69 Ma (Bundtzen and others, 1998).
Alteration of deposit Tourmaline-axinite (greisen).

Production and reserves

Workings or exploration Surface sampling was conducted by the Alaska Division of Geological and Geophysical Surveys in 1990 (Bundtzen and others, 1998).
Indication of production None