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

Geologic information

Identification information

Deposit ID 10000904
MRDS ID A011560
Record type Site
Current site name Jiles-Knudson
Alternate or previous names J + K, Purkeypile(s)

Geographic coordinates

Geographic coordinates: -152.15397, 62.90147 (WGS84)
Relative position C.C. Hawley and Associates, Inc. (1978, Fig. 4.2-C and Fig. 4.2C(3)-A(1)) show the J+K adit in schist near the granite contact about 1/2 mile below Boulder Creek Glacier on the east bank of Boulder Creek in the southeast quarter of Section 32, T. 33 N., R. 15 W., of the Seward Meridian.
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Geographic areas

Country State
United States Alaska


Commodity Importance
Silver Primary
Gold Primary
Copper Primary
Lead Primary
Arsenic Secondary
Manganese Secondary
Antimony Secondary
Zinc Secondary

Comments on the commodity information

  • Gangue = manganese oxides
  • Ore Material = argentiferous galena

Materials information

Materials Type of material
Arsenopyrite Ore
Chalcopyrite Ore
Malachite Ore
Pyrite Ore
Pyrrhotite Ore
Sphalerite Ore
Silver Ore
Galena Ore
Goethite Gangue
Siderite Gangue


  • (Local) Development of skarn assemblage in Paleozoic country rocks (C.C. Hawley and Associates, Inc., 1978).

Mineral occurrence model information

Model code 47
USGS model code 15b
Deposit model name Sn veins
Model code 43
USGS model code 14b
Deposit model name Sn skarn

Host and associated rocks

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

Nearby scientific data

(1) -152.15397, 62.90147

Comments on the geologic information

  • Geologic Description = The Jiles-Knudson prospect is located on the west side of the Boulder Creek drainage, the geologic setting of which is provided, as follows, from work 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 Tertiary Tonzona granitic pluton (Tmt), part of the McKinley sequence of 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 in the granite 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, silver and tin mineralization occurs in lower Paleozoic metasediments and metavolcanic rocks along the north and northeast contact of the pluton. ? At this site a short adit (J+K adit), dozer cuts and diamond drill holes have been used to explore the Jiles-Knudson property. The prospect is a lenticular body of pyrrhotite-rich skarn, 3 to 10 feet thick, that contains pods of galena, pyrite, arsenopyrite, possible tetrahedrite, and other sulfides stratabound within Paleozoic limestone (C.C. Hawley and Associates, Inc., 1978; Reed and others, 1978). The body strikes about N85E and dips 80 degrees to the north and is exposed for about 140 feet. The sulfide body has been exposed in an open cut, a 15 foot shaft, eleven-foot adit and trench. The pyrrhotite-rich skarn runs 0.7 to 0.9% copper. One sample of gossan from the shaft dump contained 3.22 oz/ton Ag. Another gossan sample contained 0.96% lead. An eleven-foot sample from pyrrhotite-rich material in place carried 0.96 oz/ton gold. (Maloney and Thomas, 1966, Table 5; C.C. Hawley and Associates, Inc., 1978).? In the entire Boulder Creek area there are widely separated, mineralized outcrops. Mapping and ground geophysical surveys, including magnetics and Chrone VLF, suggest extensive skarn development and skarn mineralization across Boulder Creek from the J+K adit. Little sub-surface exploration has been completed. Although tin is not specifically reported from the Jiles-Knudson prospect, its proximity to the Boulder Creek (TL073) suggests that it is part of the same mineralizing system. ? In much of the published literature the Purkeypile group of lode claims includes Boulder Creek (TL073), Hogback ( TL006) and Mespelt (TL005) prospects.
  • Age = Tertiary; mineralization in the Jiles-Knudson area 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

Comments on exploration

  • Status = Undetermined.

Mining district

District name McGrath

Comments on the workings information

  • Workings / Exploration = F. B. Jules and Ed Knutson of Poorman, Alaska concentrated their effort on the Jiles-Knudson prospect between 1910(?) and 1923. Mr. I.W. Purkeypile and son David Purkeypile 'rediscovered' and prospected the Boulder Creek area since the late 1940s (C.C. Hawley and Associates, Inc., 1978). The area was evaluated by numerous private mining companies in the 1970s and 1980s. ? Workings at the Jiles-Knudson include an open cut, a 15 foot shaft, 11 foot adit and trench ( C.C. Hawley and Associates, Inc., 1978, Fig. 4.2-C and Fig. 4.2C(3)-A(1)).

Reference information

Links to other databases

Agency Database name Acronym Record ID Notes
USGS Mineral Resources Data System MRDS A011560
USGS Alaska Resource Data File ARDF TL004

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

    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

    Warner, J.D., 1985, Critical and strategic minerals in Alaska: tin, tantalum, and columbium: U.S. Bureau of Mines Information Circular 9037, 42 p.

  • Deposit

    Nokleberg, W.J., Bundtzen, T.K., Berg, H.C., Brew, D.A., Grybeck, D.J., Robinson, M.S., Smith, T.E., and Yeend, W., 1987, Significant metalliferous lode deposits and placer districts of Alaska: U.S. Geological Survey Bulletin 1786, 104 p.

  • 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

    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) or related to Sn Skarn Deposits (Cox and Singer, 1986; model 14b).
Deposit Other Comments = Although tin is not specifically reported from the Jiles-Knudson property, its proximity to the Boulder Creek tin lodes suggests that it is very likely part of the same mineralization and alteration event. Thus the inclusion of Jiles-Knudson in model 14b is based on that interpretation. Most post-1970 prospecting has centered on tin-silver mineralization in the Boulder Creek area.? the Purkeypile group of lode claims includes Jiles-Knudson (this record), Boulder Creek (TL073), Mespelt (TL005) and Hogback (TL006) prospects.

Reporter information

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