Mahoney

The Mahoney is a lead and zinc mine located in Alaska.

About the MRDS Data:

All mine locations were obtained from the USGS Mineral Resources Data System. The locations and other information in this database have not been verified for accuracy. It should be assumed that all mines are on private property.

Mine Info

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Site Name

Primary: Mahoney
Secondary: Ash
Secondary: Asche

Commodity

Primary: Lead
Primary: Zinc
Secondary: Copper
Secondary: Cadmium
Secondary: Gold
Secondary: Silver

Location

State: Alaska
District: Ketchikan

Land Status

Not available

Holdings

Not available

Workings

Not available

Ownership

Not available

Production

Not available

Deposit

Record Type: Site
Operation Category: Past Producer
Operation Type: Unknown
Years of Production:
Organization:
Significant:

Physiography

Not available

Mineral Deposit Model

Not available

Orebody

Not available

Structure

Not available

Alterations

Not available

Rocks

Not available

Analytical Data

Not available

Materials

Ore: Sphalerite
Ore: Galena
Gangue: Quartz
Gangue: Calcite

Comments

Comment (Deposit): Model Name = Stratiform, massive-sulfide replacement body

Comment (Deposit): Other Comments = Early reports refer to this property as the Asche, or Ash, claim (Brooks, 1902, p. 63-64; Cobb and Elliott, 1980, p. 71).

Comment (Reference): Primary Reference = Robinson and Twenhofel, 1953; Maas and others, 1995

Comment (Reserve-Resource): Reserves = Resources are estimated at 2,500 tons of material averaging 6-7% Pb and about 28% Zn (Robinson and Twenhofel, 1953; Cobb and Elliott, 1980, p. 71).

Comment (Workings): Workings / Exploration = The Mahoney deposit was discovered in the early 1900s and originally referred to as the Asche claim (Brooks, 1902, p. 63). The mine was developed mainly in the 1940s and included more than 600 feet of underground workings, along with several surface pits and trenches (Maas and others, 1995, p. 202). From 1947-49, total recovery from about 400-500 tons of ore was 33.1 metric tons (mt) of Zn, 18.1 mt of Pb, 1.27 mt of Cu, 11.6 kg of Ag, and 0.25 kg of Au (Maas and others, 1995, p, 202). ? Maas and others (1995, p. 210) collected one-foot-wide samples across the deposit for the first 118 feet of the main adit. These samples averaged 3.2% Pb, 7.6% Zn, 25.5 ppm Ag. The weighted average of assays of 1.4-foot-long samples along 60 feet of the richest ore was 20.1% Zn, 8.0% Pb, 61 ppm Ag, and 0.69 ppm Au (Maas and others, p. 204). Some samples also contained up to 1200 ppm Cd. Maas and others' sampling showed a direct correlation between high lead and silver values.

Comment (Geology): Geologic Description = The country rocks in this part of Revillagigedo Island are marine, pelitic phyllite and schist that are intruded by Cretaceous stocks, sills, and dikes of feldspar-porphyritic granodiorite, and by a stock and probably related plugs of Tertiary gabbro (Berg and others, 1988). The strata and some of the granodiorite were regionally metamorphosed to greenschist grade in Late Cretaceous time. These regionally metamorphosed rocks subsequently were locally contact metamorphosed to hornblende hornfels near the contacts of Cretaceous granodiorite plutons that were emplaced after the regional metamorphism, and then more widely remetamorposed to hornblende hornfels near the contacts of the Tertiary gabbro. The premetamorphic age range of the pelitic strata is uncertain. Berg and others (1988) assign them a Mesozoic or (Late) Paleozoic age; Brew and Ford (1998) and Crawford and others (in press) assign them to the Gravina belt, of Late Jurassic or Cretaceous age.? the Mahoney deposit consists of a pod or lens 6 inches to 3 feet thick and 350 feet long of massive sphalerite and galena, accompanied by interstitial quartz and calcite. The orebody formed by fracture filling in, and by minor replacement of, dark gray, graphitic, slaty to phyllitic metapelite (Robinson and Twenhofel, 1953; Cobb and Elliott, 1980, p. 71). The metapelite locally is intruded by feldspar-porphyritic dikes or sills. ? Maas and others (1995, p. 203-204) note that the deposit has a shallow dip and is slightly discordant to the gently-dipping foliation of the phyllite hostrock. The orebody thickens from west to east and its dip steepens from 17 to 54 degrees. They believe that the deposit was emplaced along a fault, or, more likely, that there has been fault movement along the boundary of the soft sulfides and the relatively hard phyllite. Where the massive sulfides are not present, the fault zone is filled with quartz and crushed phyllite.? the Mahoney deposit was discovered in the early 1900s and originally referred to as the Asche claim (Brooks, 1902, p. 63). The mine was developed mainly in the 1940s and included more than 600 feet of underground workings, along with several surface pits and trenches (Maas and others, 1995, p. 202). From 1947 to 1949, total recovery from about 400-500 tons of ore was 33.1 metric tons (mt) of Zn, 18.1 mt of Pb, 1.27 mt of Cu, 11.6 kg of Ag, and 0.25 kg of Au (Maas and others, 1995, p, 202). Resources are estimated at 2,500 tons of material averaging 6-7% Pb and about 28% Zn (Robinson and Twenhofel, 1953; Cobb and Elliott, 1980, p. 71).? Maas and others (1995, p. 210) collected one-foot-wide samples across the deposit for the first 118 feet of the main adit. These samples averaged 3.2% Pb, 7.6% Zn, and 25.5 ppm Ag. The weighted average of assays of 1.4-foot-long samples along 60 feet of the richest ore was 20.1% Zn, 8.0% Pb, 61 ppm Ag, and 0.69 ppm Au (Maas and others, p. 204). Some samples also contained up to 1200 ppm Cd. Maas and others' sampling showed a direct correlation between high lead and silver values.

Comment (Production): Production Notes = From 1947 to 1949, total recovery from about 400-500 tons of ore was 33.1 metric tons (mt) of Zn, 18.1 mt of Pb, 1.27 mt of Cu, 11.6 kg of Ag, and 0.25 kg of Au (Maas and others, 1995, p, 202). Resources are estimated at 2,500 tons of material averaging 6-7% Pb and about 28% Zn (Cobb and Elliott, 1980, p. 71).

References

Reference (Deposit): Crawford, M.L., Crawford, W.A., and Gehrels, G.E., 2000, Terrane assembly and structural relationships in the eastern Prince Rupert quadrangle, British Columbia, in H.H. Stowell and W.C.McClelland, eds., Tectonics of the Coast Mountains, southeastern Alaska and British Columbia: Boulder, Colorado, Geological Society of America Special Paper 343, p. 1-21.?

Reference (Deposit): Brew, D.A., and Ford, A.B., 1998, The Coast Mountains structural zones in southeastern Alaska--descriptions, relations, and lithotectonic significance, in Gray, J.E., and Riehle, J.R., eds., The U.S. Geological Survey in Alaska--geological studies in Alaska by the U.S. Geological Survey in 1996: U.S. Geological Survey Professional Paper 1595, p. 183-192.

Reference (Deposit): Maas, K.M., Bittenbender, P E., and Still, J.C., 1995, Mineral investigations in the Ketchikan mining district, southeastern Alaska: U.S. Bureau of Mines Open-File Report 11-95, 606 p.

Reference (Deposit): 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 MF-1807,27 p., scale 1:250,000.

Reference (Deposit): Cobb, E.H., and Elliott, R.L., 1980, Summaries of data on and lists of references to metallic and selected nonmetallic mineral deposits in the Ketchikan and Prince Rupert quadrangles, Alaska: U.S. Geological Survey Open-File Report 80-1053, 154 p.

Reference (Deposit): Elliott, R.L., Berg, H.C., and Karl, Susan, 1978, map and table describing metalliferous and selected nonmetalliferous mineral deposits, Ketchikan and Prince Rupert quadrangles, Alaska: U.S. Geological Survey Open-file Report, 78-73-B,17 p., scale 1:250,000.

Reference (Deposit): Brooks, A.H., 1902, Preliminary report on the Ketchikan mining district, Alaska, with an introductory sketch of the geology of southeastern Alaska: U.S. Geological Survey Professional Paper 1, 120 p.

Reference (Deposit): Robinson, G.D., and Twenhofel, W.S., 1953, Some lead-zinc and zinc-copper deposits of the Ketchikan and Wales districts, Alaska: U.S. Geological Survey Bulletin 998-C, p. 59-84.

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