Holkham Bay

Mine, Probably inactive

Commodities and mineralogy

Main commodities Ag; Au; Cu; Pb
Ore minerals chalcopyrite; galena; gold; pyrite
Gangue minerals quartz

Geographic location

Quadrangle map, 1:250,000-scale SD
Quadrangle map, 1:63,360-scale C-4
Latitude 57.59483
Longitude -133.23972
Nearby scientific data Find additional scientific data near this location
Location and accuracy This site is plotted at the upper workings of the Holkam Bay Mine at an elevation of about 2,085 feet. The mine is about 0.5 mile west-northwest of the center of section 28, T. 49 S. R. 76 E. The lower workings of the property are about 900 feet northwest at an elevation of about 1,715 feet.

Geologic setting

Geologic description

The Holkam Bay Mine was discovered about 1900 and was being explored underground by 1906 (Spencer, 1906; Kimble and others, 1984). The deposit consists of three quartz veins in Cretaceous graphitic or siliceous schist, part of the biotite schist unit of Brew and Grybeck (1984).
One vein has been explored by a 170-foot drift and three stopes to the surface. This vein is 1-2 feet thick and can be traced underground and in surface pits for 400 feet. It strikes about N30W and dips 40-45W. The vein contains minor free gold, galena, pyrite, and chalcopyrite. Kimble and others (1984) collected 50 samples in the workings. The best contained 4.89 ounces of gold per ton across 0.9 feet. The rest contained nil to 0.61 ounce of gold per ton and average about 0.09 ounce of gold per ton. Most samples contained a trace to a few parts per million silver. None of the samples, however, contained any other metals of significance other than a few that showed slightly anomalous zinc or lead. A small Gibson mill was put in operation in 1940 and milled a small amount of ore (Kloss, 1940). From the size of the stopes, Kimble and others (1984) estimate that about 20 to 50 ounces of gold was produced. There has been little if any activity on the property since the early 40s.
There is another parallel, near-vertical quartz vein about 500 feet to the east that can be traced for about 400 feet. It is about 6 feet thick and was traced in a series of shallow shafts and open cuts. A crosscut was started to intersect it at depth but stopped short of doing so. Downhill to the southeast, there is a third vein that may be the extension of the second vein that can be traced for about 400 feet. It trends N40W and dips 60NE to vertical.
The deposits at the nearby Marty prospect (SD041) and the Sumdum Chief Mine (SD028) have been dated at about 55 million years (Goldfarb and others, 1997). This prospect is geologically similar and probably of the same age. Goldfarb and others (1997) also propose that most gold-quartz vein deposits along the Juneau Gold Belt such as this one were formed from fluids generated by Cretaceous metamorphism and then forced to the site of deposition by the emplacement of the Coast Range Batholith.
Geologic map unit (-133.241423826991, 57.5944915919677)
Mineral deposit model Low-sulfide, gold-quartz vein (Cox and Singer, 1986; model 36a).
Mineral deposit model number 36a
Age of mineralization The deposits at the nearby Marty prospect (SD041) and the Sumdum Chief Mine (SD028) have been dated at about 55 million years (Goldfarb and others, 1997). This prospect is geologically similar and probably of the same age.

Production and reserves

Workings or exploration One vein has been explored with a 170-foot drift and three stopes to the surface.
Indication of production Yes; small
Production notes A small Gibson mill was put in operation in 1940 and milled a small amount of ore (Kloss, 1940). From the size of the stopes, Kimble and others (1984) estimate that about 20 to 50 ounces of gold was produced. There has been little if any activity on the property since the early 1940s.

Additional comments

The mine is in the Chuck River Wilderness Area which is closed to prospecting and mining.

References

MRDS Number A013338

References

Reporters Donald Grybeck (U.S. Geological Survey)
Last report date 10/8/2004