Mount Henry Clay

Prospect in Alaska, United States with commodities Silver, Gold, Barium-Barite, Copper, Lead, Zinc

Geologic information

Identification information

Deposit ID 10002195
MRDS ID A013093
Record type Site
Current site name Mount Henry Clay
Related records 10233817

Geographic coordinates

Geographic coordinates: -136.46214, 59.38974 (WGS84)
Relative position This location is the approximate center of a 1/2 mile long arcuate pattern of mineralized float below a small hanging glacier. Most of the mineralized float is between about 4,200 and 4,400 feet in elevation in a narrow septum of rock and talus between glaciers; it is located about 1 mile north-northeast of Mt. Henry Clay and within 1/2 mile of the Canada-United States border. It is shown as location 21 in figure 6 by Still (1984 [OF 118-84]).
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Geographic areas

Country State
United States Alaska

Commodities

Commodity Importance
Silver Primary
Gold Primary
Barium-Barite Primary
Copper Primary
Lead Primary
Zinc Primary

Comments on the commodity information

  • Ore Material = argentiferous galena

Materials information

Materials Type of material
Barite Ore
Bornite Ore
Chalcopyrite Ore
Gold Ore
Pyrite Ore
Sphalerite Ore
Silver Ore
Galena Ore
Calcite Gangue
Chlorite Gangue
Epidote Gangue
Quartz Gangue

Alteration

  • (Local) Chloritic.

Mineral occurrence model information

Model code 184
USGS model code 28a
Deposit model name Massive sulfide, kuroko
Mark3 model number 93
Model code 91
USGS model code 24b
Deposit model name Massive sulfide, Besshi (Japanese deposits)
Mark3 model number 30

Host and associated rocks

  • Host or associated Host
    Rock type Volcanic Rock (Aphanitic) > Intermediate Volcanic Rock > Andesite
    Stratigraphic age (youngest) Late Permian

Nearby scientific data

(1) -136.46214, 59.38974

Comments on the geologic information

  • Geologic Description = According to Still (1984 [OF 118-84]), the Mt. Henry Clay prospect is located within the Glacier Creek volcanic-sedimentary sequence that hosts all of the Glacier Creek volcanogenic massive-sulfide occurrences. The sequence includes basalt, which locally display good pillow structures, andesitic flows and tuffs, and minor sedimentary rocks. The andesitic flows and tuffs in the vicinity of Mt. Henry Clay are mostly altered to chloritic phyllites. Exposed mineralization consists of sphalerite-barite-pyrite-chalcopyrite boulders up to 6 feet in diameter that are found along a sliver of rock that extends for a distance of 1/2 mile beneath the toe of a small triangular-shaped hanging glacier. Bedrock exposures of mineralization were not found and the source of the mineralized boulders is probably beneath the glacier. Assays of the mineralized float are variable; the highest grade samples contain 20 to 44% zinc, 5% barium, and several percent copper. Ore-grade mineralization was not found in place, but elevated levels of zinc, copper, barium, lead, silver, and gold were found in altered andesites in the area.? Diamond drilling by Kennecott Exploration intersected felsic schists that contained barite-sphalerite mineralization underlain by pyrite-chalcopyrite stringer zones in chloritized basalt. Their drill core assays included intervals from 20 to 161 feet thick that contained up to 0.70% zinc and 0.44% copper. Drilling by Stryker Resources and Freeport Resources on the Canadian side of the border returned similar values. (Still and others, 1991; Rosenkrans and Jones, 1985).? Eleven drill holes, 7 by Kennecott Exploration and 4 by Granges, Inc. totaling 8,719 feet, identified two mineralized horizons but did not intercept high grade mineralization comparable to the surface boulders. Rubicon Minerals interprets the Mount Henry Clay prospect to to be on a mineral trend along or near the apex of a shallowly plunging, northwest-trending antiform that extends to the southeast through the Cap (SK060) and Nunatak (SK058) prospects. (Rubicon Minerals, 1998). The Mt. Henry Clay prospect 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 [OF 118-84]); Newberry and others, 1997).
  • Age = The Mt. Henry Clay prospect 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 [OF 118-84]; Newberry and others, 1997).

Economic information

Economic information about the deposit and operations

Development status Prospect
Commodity type Both metallic and non-metallic

Comments on exploration

  • Status = Active

Mining district

District name Juneau (Skagway subdistrict)

Comments on the workings information

  • Workings / Exploration = Stryker Resources drilled 5 holes totaling 2,787 feet in length on extensions of this occurrence on the Canadian side of the border in 1985 (Still and others, 1991; Rosenkrans and Jones, 1985). Eleven drill holes, 7 by Kennecott Alaska Exploration and 4 by Granges, Inc. totaling 8,719 feet identified two mineralized horizons but did not intercept high grade mineralization comparable to boulders found at the surface (Rubicon Minerals, 1998).

Reference information

Links to other databases

Agency Database name Acronym Record ID Notes
USGS Mineral Resources Data System MRDS A013093
USGS Alaska Resource Data File ARDF SK068

Bibliographic references

  • 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.

  • 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.

  • Deposit

    Rosenkrans, D.S., and Jones, B.K., 1985, Jarvis Glacier project, 1985 annual progress report: Kennecott Alaska Exploration report, 30 p. (Unpublished material available at the Juneau Mineral Information Center, U.S. Bureau of Land Management, Juneau, Alaska).

  • Deposit

    Forbes, R.B., Gilbert, W.G., and Redman, E., 1989, Geologic setting and petrology of the metavolcanic rocks in the northwestern part of the Skagway B-4 Quadrangle, southeastern Alaska: Alaska Division of Geological and Geophysical Surveys Public-Data File 89-14, 46 p.

  • Deposit

    Gilbert, W.G., and Redman, E.C., 1989, Lode deposits, prospects, and occurrences of the Porcupine mining area, southeast Alaska: U.S. Bureau of Mines Open-File Report 17-89, 1 sheet, scale 1:39,600.

  • Deposit

    Still, J.C., 1991, Bureau of Mines mineral investigations in the Juneau mining district, Alaska, 1984 - 1988, v. 2, Detailed mine, prospect, and mineral occurrence descriptions, section A, Haines-Klukwan-Porcupine subarea: U.S. Bureau of Mines of Mines Special Publication, 214 p.

  • Deposit

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

  • 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.

Comments on the references

  • Primary Reference = Still, 1984 (OF 118-84)

General comments

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

Reporter information

Type Date Name Affiliation Comment
Reporter 04-FEB-2001 T.C. Crafford T. Crafford & Associates