|Quadrangle map, 1:250,000-scale||KC|
|Quadrangle map, 1:63,360-scale||D-3|
|Nearby scientific data||Find additional scientific data near this location|
|Location and accuracy||The Gnat prospect is at an elevation of about 150 feet in a narrow gorge in the north wall of Chickamin River canyon, about 1250 feet N22W of Wolf cabin at the mouth of the Chickamin River. The site is in section 6, T. 70 S., R. 95 E., of the Copper River Meridian. It corresponds to loc. P-20 in Berg and others (1977, p. 121), and loc. 21 in Elliott and others (1978). The location is accurate within about 300 feet.|
The country rocks in the area of the Gnat prospect is Tertiary or Cretaceous gneissic quartz diorite of the Coast Range batholith that locally contains inclusions of metasedimentary rocks (Berg and others, 1988). The quartz diorite near the prospect is cut by at least one two-foot-thick dike of altered felsic rock (Berg and others, 1977, p. 121).The Gnat prospect consists of a glassy quartz-albite fissure vein 5.5 feet to 9.5 feet thick that strikes N20W and dips 59-80NE (Berg and Cobb, 1967, p. 182-183; Berg and others, 1977, p. 121). The vein is in gneissic quartz diorite and contains chalcopyrite, molybdenite, galena, and pyrite. The sulfides are relatively abundant for about 1.5 feet below the hanging wall; the rest of the vein is low in visible sulfides. Several channel and composite samples of the vein and of float probably derived from the vein assayed up to 1400 ppm Cu, 1500 ppm Pb, and 4700 ppm Mo (Berg and others, 1977, table 12). The Gnat deposit was staked about 1900, when the vein probably was prospected chiefly for gold (Buddington, 1929, p. 120 [B 807]; Berg and Cobb, 1967, p. 182-183). There is no record of any workings, or of any recovery of gold from the vein, but there probably was some small early production.
|Geologic map unit||(-130.910706261281, 55.8306494594908)|
|Mineral deposit model||Polymetallic vein (Cox and Singer, 1986; model 22c)|
|Mineral deposit model number||22c|
|Workings or exploration||The Gnat deposit was staked about 1900, when the vein probably was prospected chiefly for gold (Buddington, 1929, p. 120; Berg and Cobb, 1967, p. 182-183). Several channel and composite samples of the vein and of float probably derived from the vein assayed up to 1400 ppm Cu, 1500 ppm Pb, and 4700 ppm Mo (Berg and others, 1977, table 12).|
|Indication of production||Undetermined|
|Production notes||There is no record of any workings, or of any recovery of gold from the vein, but there probably was some small early production.|
Additional commentsThe site is in Misty Fiords National Monument Wilderness.
Berg, H.C., and Cobb, E.H., 1967, Metalliferous lode deposits of Alaska: U.S. Geological Survey Bulletin 1246, 254 p.
Berg, H.C., Elliott, R.L., and Koch, R.D., 1988, Geologic map of the Ketchikan and Prince Rupert quadrangles, southeastern Alaska: U.S. Geological Survey Mineral Investigations Series Map I-1807, 27 p., scale 1:250,000.
Berg, H.C., Elliott, R.L., Smith, J.G., Pittman, T.L., and Kimball, A. L., 1977, Mineral resources of the Granite Fiords Wilderness Study Area, Alaska, with a section on aeromagnetic data by Andrew Griscom: U.S. Geological Survey Bulletin 1403, 151 p.
Buddington, A.F., 1929, Geology of Hyder and vicinity, southeastern Alaska, with a reconnaissance of Chickamin River: U.S. Geological Survey Bulletin 807, 124 p.
|Reporters||H.C. Berg, USGS|
|Last report date||6/29/1999|