|Quadrangle map, 1:250,000-scale||PA|
|Quadrangle map, 1:63,360-scale||D-4|
|Nearby scientific data||Find additional scientific data near this location|
|Location and accuracy||The Bauer prospect is shown by symbol on the 1:63,360-scale topographic map. It is 1.7 mile northwest of the center of Pinta Lake and about 0.2 mile east of the center of section 32, T. 56 S., R. 65 E. The underground workings are mapped by Bittenbender and others (1999, fig. 26).|
This deposit is one of many of similar deposits (PA002 to PA018) scattered over an area of about 6 square miles at the head of Silver Bay (Bittenbender and others, 1999). The deposits are gold-quartz veins with sparse sulfides, usually only pyrite and arsenopyrite. Samples that have been analyzed with modern methods usually show anomalous arsenic even if arsenopyrite is not identified in the rocks, and several parts per million mercury. The veins are often parallel to the bedding of the host rock which is graywacke and argillite of the Sitka Graywacke of Cretaceous age (Loney and others, 1975). Many of the so-called veins in the early literature are actually fault zones with lenses of quartz or concentrations of quartz stringers along the fault zone. Prospecting began in the area in 1871. The Stewart Mine (PA012) was located in 1872 and it was the first lode-gold mine in Alaska. The Silver Bay area has been prospected intermittently to the present but the veins are relatively small and most are low grade. The area has produced relatively little gold, many of the properties have not been active since before 1900, and there has been no production since the early 1940s.The Bauer prospect was staked in 1895 (Becker, 1897) and was active intermittently to 1923. By 1904, at least 850 feet of adit had been driven (Wright and Wright, 1905), and in 1912, 180 feet of drift was driven off the end of the adit Knopf, 1912). Bittenbender and others (1999) mapped and sampled what are probably all of the old workings. Most of the adit is in graywacke and phyllite. The drift at the end of the adit is along a fault zone marked by fine-grained quartz and quartz stringers with minor pyrite, arsenopyrite, and pyrrhotite. Samples contained low precious metal values. The highest value was in a sample across 1.5 feet of the fault zone; it contained 280 parts per billion gold. That sample also contained 716 parts per million (ppm) arsenic and 1.1 ppm mercury. Becker (1897) noted that there was a rich pay streak along the footwall of a quartz vein several feet thick. Wright and Wright (1905) said that the main vein averaged about $4.50 in gold (about 0.22 ounce of gold per ton).
|Geologic map unit||(-135.108583478504, 56.9692829956742)|
|Mineral deposit model||Low-sulfide, gold-quartz vein (Cox and Singer, 1986; model 36a).|
|Mineral deposit model number||36a|
|Age of mineralization||Cretaceous or younger based on the age of the country rocks.|
|Workings or exploration||The workings consist of an adit at least 850 feet long and a 180-foot drift off the end of the adit; all of the workings were driven before 1912.|
|Indication of production||Undetermined|
|Production notes||No record of production.|
Additional commentsMAS number: 0021160005.
Bittenbender, P., Still, J.C., Maas, K., and McDonald, M., Jr., 1999, Mineral resources of the Chichagof and Baranof Islands area, southeast Alaska: Bureau of Land Management, BLM-Alaska Technical Report 19, 222 p.
DeArmond, R.N., 1997, Haleys and Silver Bay, in Around and About Alaska: Sitka Sentinel, series of 29 Articles, April to October, 1997.
Loney, R.A., Brew, D.A., Muffler, L.J. B., and Pomeroy, J.S., 1975, Reconnaissance geology of Chichagof, Baranof, and Kruzof Islands, southeastern Alaska: U.S. Geological Survey Professional Paper 792, 105 p.
|Reporters||Donald J. Grybeck (U.S. Geological Survey)|
|Last report date||2-Jan-05|