Niblack

Mine, Active

Commodities and mineralogy

Main commodities Ag; Au; Cu; Zn
Other commodities Pb
Ore minerals chalcopyrite; galena; hematite; pyrite; sphalerite

Geographic location

Quadrangle map, 1:250,000-scale CR
Quadrangle map, 1:63,360-scale A-1
Latitude 55.0666
Longitude -132.1475
Nearby scientific data Find additional scientific data near this location
Location and accuracy
This site is the old Niblack Mine that operated from 1902 to 1909. It is just above the shoreline at the head of Niblack Anchorage. It is identified on the USGS 1:63,360-scale topographic map by the name of the old settlement, and it is about 0.6 mile east-northeast of the center of section 33, T. 78 S., R. 88 E.
From the late 1970's to the present (2004), there has been nearly continuous exploration of several geologically similar deposits in an area of about a square mile southeast of the old Niblack Mine. Those deposits are described separately (CR217-223), but in the recent literature, the Niblack Mine and other deposits in the area are commonly grouped together under the name 'Niblack,' or 'Niblack project'. In 2010, most of the work is concentrated on an orebody near the old Lookout prospect (CR221) which is often identified as the 'Niblack project' or 'Niblack'.

Geologic setting

Geologic description

The deposit at the Niblack Mine was first developed in 1902 and soon was put in production (Brooks, 1902; Wright and Wright, 1908; Berg and Cobb, 1967). Production continued until 1909, when the mine was closed due to legal actions and it has not produced since. The total production (from incomplete records) is 1,400,000 pounds of copper, 1,100 ounces of gold, and 15,000 ounces of silver. The mine was worked from several shafts, one to a depth of 300 feet. There were 5 levels of workings with a total of about 5,500 feet of drifts, raises, and winzes. Roppel (1991) provides a fascinating study of the personalities and the travails of mining at Niblack.
The deposit that was mined consisted of three large masses of sulfides, 90 to 200 feet long, 5 to 20 feet thick, and 50 to 100 feet deep, that were cut by numerous faults. The ore bodies consisted largely of pyrite and chalcopyrite, with minor sphalerite, galena, and hematite. In the older publications, the host rocks are described as greenstone schist with bands of quartzite, metamorphosed sandstone, and quartz-sericite schist.
Beginning in the mid-70s, a succession of companies, including Cominco-Alaska, Inc., Anaconda Minerals, Noranda Exploration, Houston Oil and Minerals, Lac Minerals, Abacus Minerals Corp., Niblack Mining Corp., Committee Bay Resources Ltd., and the operator as of early 2010, CBR Gold Corporation (2010) have carried out extensive exploration on several deposits in the Niblack Mine area (CR217-223), testing the now widely accepted theory that they are volcanogenic, stratabound, massive-sulfide deposits (Ghayemghamian, 2010). Those deposits are commonly referred to as the 'Niblack' or 'Niblack Project'. However most of the work since at least 2005, has been concentrated on mineralization near the old Lookout prospect (CR221) that is best know and studied deposits. There has apparently been little recent work at the old Niblack Mine although Cominco-America drilled 6 holes near it in the mid-1970s.
The rocks in the area are part of the Ordovician to Lower Silurian, Moira Sound unit. Locally, the rocks consist of footwall dacite and rhyodacite; the Lookout rhyolite that hosts the massive-sulfide mineralization; and hanging wall, mafic volcanic and volcaniclastic rocks (Maas and others, 1995; Ghayemghamian and others, 2010). Rhyolite from near the Lookout prospect has a U-Pb age of 476.7 +/- 1.5 Ma (Ordovician) (Karl and others, 2009). The rocks are metamorphosed to greenschist facies. The structure in the area is dominated by several large north-verging folds and two major faults are known. Karl and others (2009) interpret the environment of deposition as a rifted, oceanic arc.
The sulfide mineralization was emplaced on the sea floor in porous, unconsolidated fragmental, volcanic sediments, resulting in zones of semi-massive and massive sulfide bodies up to 20 feet thick, dominated by chalcopyrite, pyrite, and sphalerite, that generally follow the sedimentary layering (Maas and others, 1995; Ghayemghamian and others, 2010). The massive-sulfide bodies often grade laterally into disseminated, stringer, and replacement sulfides. The main metals of economic significance are copper, zinc, gold, and silver; lead is low and arsenic, antimony, cadmium, mercury, and selenium are too low to pose a metallurgical problem.
Geologic map unit (-132.149150261415, 55.0662513925129)
Mineral deposit model Besshi-type volcanogenic Ag-Au-Cu massive-sulfide deposit (Cox and Singer, 1986; model 24b).
Mineral deposit model number 24b
Age of mineralization The Lookout rhyolite that hosts the mineralization has been dated at 476.7 +/- 1.5 Ma (Ordovician).
Alteration of deposit Not specifically noted, but probably typical of volcanogenic massive-sulfide deposits.

Production and reserves

Workings or exploration
The deposit at the Niblack Mine was first developed in 1902 and soon was put in production (Brooks, 1902; Wright and Wright, 1908). Production continued until 1909, when the mine was closed due to legal actions and it has not produced since. Roppel (1991) provides a fascinating study of the personalities and the travails of the early mining at Niblack.
Beginning in the mid-70s, a succession of companies, including Cominco-Alaska, Inc., Anaconda Minerals, Noranda Exploration, Houston Oil and Minerals, Lac Minerals, Abacus Minerals Corp., Niblack Mining Corp., Committee Bay Resources Ltd., and the operator as of early 2010, CBR Gold Corporation (2010) have carried out extensive exploration on several deposits in the Niblack Mine area (CR217-223), testing the now widely accepted theory that they are volcanogenic, stratabound, massive-sulfide deposits (Ghayemghamian, 2010). Those deposits are commonly referred to as the 'Niblack' or 'Niblack Project'. However most of the work since at least 2005, has been concentrated on mineralization near the old Lookout prospect (CR221) that is best know and studied deposits. Apparently, there has been little recent work at the old Niblack Mine although Cominco-America drilled 6 holes near it in the mid-1970s.
Indication of production Yes; small
Reserve estimates Apparently none at this, the old Niblack Mine, but considerable at what is being called the 'Niblack' or 'Niblack project', near the nearby, old Lookout prospect (CR221).
Production notes The total production of the Niblack Mine from 1902 to 1909 (based on incomplete records) was 1,400,000 pounds of copper, 1,100 ounces of gold, and 15,000 ounces of silver.

References

MRDS Number A010171; A101125

References

Brewer, N.H., 1989, Geology of the Niblack massive sulfide property, Prince of Wales Island, Alaska (abs.): Alaska Miners Association, Juneau Branch, Conference Juneau, Abstracts of Professional Papers, p. 34-35.
CBR Gold Corp, 2010, Niblack Au-Cu-Ag-Zn project: http://www.cbrgoldcorp.com/project_areas/united_states/niblack/ (as of February 28, 2010).
Ghayemghamian, Abolfazi, Nowak, Marek, and Kleespies, Peter, 2010, Mineral resource estimation, Niblack polymetallic sulphide project, Alaska, U.S.A.: Technical report for CBR Gold Corp, 177 p. (posted on www.sedar.com, February 5, 2010)
Peek, B.C., 1975, Geology and mineral deposits of the Niblack Anchorage area, Prince of Wales Island, Alaska: Fairbanks, University of Alaska, M.Sc. thesis, 50 p.
Roppel, Patricia, 1991, Fortunes from the earth: Manhattan, Kansas, Sunflower University Press, 139 p.
Slack, J.F., Shanks, W.C. III, Karl, S.M., Ridley, W.I., and Bittenbender, P.E., 2002, Geochemical and sulfur isotope compositions of Late Proterozoic and early Paleozoic volcanogenic massive sulfide deposits, Prince of Wales Island and vicinity, southeastern Alaska (abs.): Geological Society of America, Abstracts with Programs, v. 34 (6), p. 113.
Reporters D.J. Grybeck (Contractor, U.S. Geological Survey)
Last report date 4/2/2010