Hogback

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

Geologic information

Identification information

Deposit ID 10000906
MRDS ID A011562
Record type Site
Current site name Hogback
Alternate or previous names Purkeypiles, Little Mountain

Geographic coordinates

Geographic coordinates: -152.22897, 62.88563 (WGS84)
Relative position Maloney and Thomas (1966) locate the Hogback prospect in the southwest quarter of Section 2, T.32 N., R.16 W., of the Seward Meridian. It is roughly 3000 feet southwest of Little Mountain on a ridge between the headwaters of Camp Creek and Canyon Creek at about 4300 feet in elevation; about 1.0 miles southwest of the Mespelt prospect (TL005). Reed and others (1978) show this prospect as locality 4.
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Geographic areas

Country State
United States Alaska

Commodities

Commodity Importance
Silver Primary
Lead Primary
Zinc Primary
Gold Secondary
Copper Secondary

Materials information

Materials Type of material
Chalcopyrite Ore
Galena Ore
Smithsonite Ore
Sphalerite Ore
Calcite Gangue
Fluorite Gangue
Goethite Gangue
Quartz Gangue

Alteration

  • (Local) Quartz-fluorite alteration developed with vein assemblage. Country rocks are converted to skarn minerals (Maloney and Thomas, 1966; C.C. Hawley and Associates, Inc., 1978).

Mineral occurrence model information

Model code 47
USGS model code 15b
Deposit model name Sn veins

Host and associated rocks

  • Host or associated Host
    Chronological age 54.25
    Uncertainty 1.95
    Stratigraphic age (youngest) Early Eocene

Nearby scientific data

(1) -152.22897, 62.88563

Comments on the geologic information

  • Geologic Description = A tractor road leads from the Mespelt prospect (TL005) to the Hogback prospect where several bulldozer cuts expose mineralized fissure veins that crosscut quartzite and limestone. The prospect consists of 3 to 4 high-grade stringers, ranging from 1.2 to 3.0 feet wide, of argentiferous galena and zinc minerals, separated by vein quartz and altered, sheared granite in a zone 32 feet wide. Quartz-fluorite alteration is developed within and adjacent to the quartz-sulfide veins. Country rocks are converted to skarn minerals (Maloney and Thomas, 1966; C.C. Hawley and Associates, Inc., 1978). Tin in the nonmagnetic heavy-mineral concentrates from stream silt samples collected by Curtin, Karlson, Tripp, and Day (1978) is in excess of 1,500 ppm from the Canyon Creek drainage to the west of this prospect.? Reed and others (1978) report the veins contain 5 to 48% lead, and 32 to 70 oz/ton silver. Maloney and Thomas (1966, Table 1) collected high-grade samples that yielded 19.30 to 134.76 oz/ton silver, trace to 0.04 oz/ton gold, 2.89 to 67.2% lead, 2.32 to 36.0% zinc, 1.2% copper. ? the geologic setting of the Hogback lead-zinc-silver vein is described, as follows, by C.C. Hawley and Associates, Inc., (1978) and Reed and Nelson (1980). Blocky slate, argillite, thin-bedded siliceous limestone and chert define a belt of lower Paleozoic sedimentary and metavolcanic rocks (possibly Keevy Peak, other Totalanika series, or equivalents) bordered by the early Tertiary Tonzona granitic pluton (Tmt), part of the McKinley sequence of intrusive rocks mapped by Reed and Nelson (1980). The granite has three phases; a coarse-grained, locally porphyritic biotite granite; a medium-grained biotite granite; and a late fine-grained, leucocratic, locally aplitic, muscovite-tourmaline granite in which ovoid clusters of small black tourmaline crystals give the rock a 'dalmatian' appearance. Muscovite may exceed biotite and accessory minerals include tourmaline with lesser amounts of topaz, fluorite, garnet, zircon, and apatite. Late-stage greissen veinlets contain muscovite, topaz, tourmaline, locally abundant beryl, and occasionally, cassiterite. Lead, zinc, and silver mineralization at the Hogback prospect occurs in the lower Paleozoic metasediments and metavolcanic rocks along the north and northeast contact of the pluton. The Tonzona pluton has metamorphosed the country rocks to skarn assemblages along the contact and has formed skarn- hosted polymetallic mineralization such as at the Jiles-Knudson (TL004), Boulder Creek (TL073) and the nearby Mespelt prospect (TL005). ? In much of the literature, the Jiles-Knudson, Mespelt, Hogback and Boulder Creek are included as the Purkeypile group of lode claims.? Despite the paucity of tin values in published analyses for the Hogback prospect, its proximity to Mespelt and the Boulder Creek tin areas and elevated tin values in streams sediment samples regionally suggests that it is part of the tin mineralizing system related to these other prospects.
  • Age = Tertiary; mineralization in the Boulder Creek, Jiles-Knudson, Mespelt and Hogback areas is interpreted to be linked to the Tonzona granite (Tmt), part of the McKinley Sequence, that has been determined to range from 52.3 to 56.2 m.y. in age (Reed and Lanphere, 1972; Reed and Nelson, 1980).
  • Age = Chron age is for McKinley Sequence.

Economic information

Economic information about the deposit and operations

Development status Prospect
Commodity type Metallic

Mining district

District name McGrath

Comments on the workings information

  • Workings / Exploration = Several bulldozer cuts have been made, and a tractor road leads from this prospect to the Mespelt Prospect (TL005).

Reference information

Links to other databases

Agency Database name Acronym Record ID Notes
USGS Mineral Resources Data System MRDS A011562
USGS Alaska Resource Data File ARDF TL006

Bibliographic references

  • Deposit

    Capps, S.R., 1925, An early Tertiary placer deposit in the Yentna district: U.S. Geological Survey Bulletin 773, p. 53-61.

  • Deposit

    Maloney, R.P., and Thomas, B.I., 1966, Investigation of the Purkeypile prospects, Kuskokwim River basin, Alaska: U.S. Bureau of Mines Open-File Report 5-66, 12 p.

  • Deposit

    Berg, H.C., and Cobb, E.H., 1967, Metalliferous Lode Deposits of Alaska. U.S. Geological Survey Bulletin 1246, 254 p.

  • Deposit

    Reed, B.L., and Lanphere, M.A., 1972, Generalized geologic map of the Alaska-Aleutian range batholith showing potassium-argon ages of the plutonic rocks: U.S. Geological Survey Miscellaneous Field Studies Map MF-372, 2 sheets, scale 1:1,000,000.

  • Deposit

    Conwell, C.N., 1977, Boulder Creek tin lode deposits: Alaska Division of Geological and Geophysical Surveys Geologic Report 55, p. 35 -38.

  • Deposit

    Curtin, G.C., Karlson, R.C., Tripp, R.B., and Day, G.W., 1978, Geochemical and generalized geologic map showing the distribution of tin, tungsten, and beryllium, Talkeetna quadrangle, Alaska: U.S. Geological Survey Miscellaneous Field Studies Map MF-870-F, 2 sheets, scale 1:250,000.

  • Deposit

    C.C. Hawley and Associates, Inc., 1978, Mineral appraisal of lands adjacent to Mt. McKinley National Park, Alaska: U.S. Bureau of Mines Open-File Report 24-78, 275 p., 7 plates.

  • Deposit

    Reed, B.L., Nelson, S.W., Curtin, G.C., and Singer, D.A., 1978, Mineral resources map of the Talkeetna Quadrangle, Alaska: U.S. Geological Survey Miscellaneous Field Studies Map MF-870-D, 1 sheet, scale 1:250,000.

  • Deposit

    Cobb, E.H., and Reed, B.L., 1980, Summaries of data and lists of reference to metallic and selected nonmetallic mineral deposits in the Talkeetna quadrangle, Alaska: U.S. Geological Survey Open-File Report 80-884, 106 p.

  • Deposit

    Reed, B.L., and Nelson, S.W., 1980, Geologic map of the Talkeetna quadrangle: U.S. Geological Survey Miscellaneous Investigations Map I-1174, scale 1:250,000.

  • Deposit

    Capps, S.R., 1927, The Toklat-Tonzona River region: U.S. Geological Survey Bulletin 792-C, p. 73-110.

  • Deposit

    MacKevett, E.M., Jr., and Holloway, C.D., 1977, Map showing metalliferous and selected non-metalliferous mineral deposits in the eastern part of southern Alaska: U.S. Geological Survey Open-File Report 77-169-A, 99 p., 1 sheet, scale 1:1,000,000.

  • Deposit

    Conwell, C.N., 1973, Grandview Exploration Company, tin and silver prospects, Talkeetna D-5 quadrangle: Alaska Divsion of Geological and Geophysical Surveys Property Examination 75-4, 42 p.

  • Deposit

    Clark, A.L., and Cobb, E.H., 1972, Metallic mineral resources map of the Talkeetna quadrangle, Alaska: U.S. Geological Survey Miscellaneous Field Studies Map MF-369, 1 sheet, scale 1:250,000.

Comments on the references

  • Primary Reference = Maloney and Thomas, 1966

General comments

Subject category Comment text
Deposit Model Name = Fringe zone of Pb, Zn, and Ag sulfide mineralization to tin veins (generally related to the tin vein model of Cox and Singer, 1986; model 15b).
Deposit Other Comments = Despite the paucity of tin values in published analyses for this prospect, its proximity to Mespelt and the Boulder Creek tin area suggests that it is the fringe part of the tin mineralizing system related to these other prospects. In much of the literature the Purkeypile group of lode claims includes Hogback, Jiles-Knudson, Mespelt and Boulder Creek.

Reporter information

Type Date Name Affiliation Comment
Reporter 10-AUG-1998 Madelyn A. Millholland Millholland & Associates