RW Zone

The RW Zone is a copper, silver, 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: RW Zone

Commodity

Primary: Copper
Primary: Silver
Primary: Zinc
Secondary: Gold

Location

State: Alaska
District: Juneau (Skagway subdistrict)

Land Status

Not available

Holdings

Not available

Workings

Not available

Ownership

Not available

Production

Not available

Deposit

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

Physiography

Not available

Mineral Deposit Model

Model Name: Massive sulfide, kuroko
Model Name: Massive sulfide, Besshi (Japanese deposits)

Orebody

Not available

Structure

Not available

Alterations

Alteration Type: L
Alteration Text: Sericitic, chloritic. The stringer zone below the massive sulfide horizon is chloritically altered.

Rocks

Not available

Analytical Data

Not available

Materials

Ore: Chalcopyrite
Ore: Barite
Ore: Sphalerite
Ore: Pyrite
Gangue: Sericite
Gangue: Quartz
Gangue: Chlorite

Comments

Comment (Geology): Geologic Description = Exploration by Rubicon Minerals in 1998 and drilling in 1999 discovered massive sulfide mineralization at the RW Zone. The RW Zone prospect is near the center of a 5-mile-long northwester trend that extends from the unnamed occurrences (SK070) at the northwest end through this prospect (SK067) and the Main Zone/Palmer prospect (SK066) to the Red Creek prospect (SK063) at the southeast end. Rubicon interprets the trend to represent the apex of a shallowly plunging, northwest-trending antiform. Mineralization intercepted in drill holes occurs both as: 1) chalcopyrite-sphalerite massive-sulfide mineralization, and 2) chalcopyrite-bearing, stringer-zone mineralization within a zone of strong chloritic alteration. The massive-sulfide, drill-intercept thicknesses range from 7.2 feet to 15 feet and contain up to 13.48% zinc, 1.89% copper, 2.98 ounces of silver per ton, and 0.02 ounces of gold per ton. Massive-sulfide drill intercepts extend over a dip length of 420 feet. The stringer-zone mineralization is beneath the massive sulfide horizon. One drill hole intercepted 156 feet of stringer-zone mineralization that included a 67.8-foot-thick interval with an average grade of 0.62% copper. Within the 67.8-foot-thick interval, there was a 16.2-foot interval that contained 1.50% copper. Surface samples from the nearby Little Jarvis prospect contain up to 13% zinc, 7% copper, and 7.0 ounces of silver per ton over a width of 15 feet. Rhyolites have been reported from the drill core. (Information summarized from Rubicon Minerals, 1998 and 1999). If the RW Zone and other similar prospects in the Mt. Henry Clay area are correlative with the Windy Craggy deposit in Canada and the Greens Creek deposit on Admiralty Island, then they are Late Triassic (Still, 1984 [OF 118-84]; Newberry and others, 1997).

Comment (Exploration): Status = Active

Comment (Reference): Primary Reference = Rubicon Minerals, 1999

Comment (Workings): Workings / Exploration = At least 6 holes were drilled on the prospect in 1999 by Rubicon Minerals. This was the first drilling in the Porcupine Creek - Mount Henry Clay area to intersect ore-grade thicknesses of massive-sulfide mineralization (Rubicon Minerals, 1999).

Comment (Geology): Age = the RW Zone and other similar prospects in the Mt. Henry Clay area are probably correlative with the Windy Craggy deposit in Canada and the Greens Creek deposit on Admiralty Island and are therefore Late Triassic (Still , 1984 (OFR 118-84); Newberry and others, 1997).

Comment (Deposit): Model Name = Kuroko- or Besshi-type volcanogenic massive-sulfide deposit (Cox and Singer, 1986; models 28a or 24b).

References

Reference (Deposit): Newberry, R.J., Crafford, T.C., Newkirk, S.R., Young, L.E., Nelson, S.W., and Duke, N.A., 1997, Volcanogenic massive sulfide deposits of Alaska, in Goldfarb, R.J. and Miller, L. D., eds., Mineral deposits of Alaska: Economic Geology Monograph 9, p. 120-150.

Reference (Deposit): Still, J.C., Hoekzema, R.B., Bundtzen, T.K., Gilbert, W.G., Wier, K.R., Burns, L.E., and Fechner, S.A., 1991, Economic geology of Haines-Klukwan-Porcupine area, southeastern Alaska: Alaska Division of Geological and Geophysical Surveys Report of Investigations 91-4, 156 p., 5 sheets, scale 1:63,360.

Reference (Deposit): Redman, E.C., 1983, Reconnaissance geology of the Glacier Creek area, Skagway B-4 quadrangle, Alaska, in Appendix B of Still, J.C., 1984, Stratiform massive sulfide deposits in the Mt. Henry Clay area, southeast Alaska: U.S. Bureau of Mines Open-File Report 118-84, 65 p.

Reference (Deposit): Rutledge, F.A., 1950, Investigation of mercury deposits, Cinnabar Creek area, Georgetown and Akiak districts, Kuskokwim region, southwestern Alaska: U.S. Bureau of Mines Report of Investigations 4719, 9 p.

Reference (Deposit): Still, J.C., 1984, Stratiform massive sulfide deposits in the Mt. Henry Clay area, southeast Alaska: U.S. Bureau of Mines Open-File Report 118-84, 65 p.

Reference (Deposit): Rubicon Minerals, 1998, Palmer VMS Project, southeast Alaska, Executive Summary: unpublished report by Rubicon Minerals Corporation, Vancouver, British Columbia, 25 p.

Reference (Deposit): MacKevett, E.M., Jr., Robertson, E.C., and Winkler, G.R., 1974, Geology of the Skagway B-3 and B-4 quadrangles, southern Alaska: U.S. Geological Survey Professional Paper 832, 33 p.

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