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Hogback

Prospect in Alaska, United States with commodities Silver, Lead, Zinc, Gold, Copper
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Sections on this page
  1. Identification information
  2. Geographic coordinates
  3. Site location context
  4. Geographic areas
  5. Commodities
  6. Materials information
  7. Alteration
  8. Mineral occurrence model information
  9. Host and associated rocks
  10. Nearby scientific data
  11. Economic information about the deposit and operations
  12. Mining district
  13. Links to other databases
  14. Bibliographic references
  15. General comments
  16. Reporter information

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.

Site location context

Political divisions (FIPS codes)

Denali(Borough)

Alaska(state)

United States(country)

North America(continent)

Land(continent)

USGS map quadrangles

Talkeetna D-5(quadrangle 1:63,360 scale)

Talkeetna NW(quadrangle 1:100,000 scale)

Talkeetna(quadrangle 1:250,000 scale)

Hydrologic units (watersheds)

North Fork Kuskokwim River(hydrologic unit)

Upper Kuskokwim River(hydrologic accounting unit)

Southwest(hydrologic subregion)

Alaska(hydrologic region)

Geographic areas

Country State
United States Alaska

Commodities

Commodity Importance
Silver Primary
Lead Primary
Zinc Critical 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
    Rock type
    Stratigraphic age (youngest) Early Eocene
    Chronological age 54.25

Nearby scientific data

(1) -152.22897, 62.88563
ListMap

Economic information

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 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

Bibliographic references

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

Beyond USGS

Supplemental information added by qvyshift.com. Not part of the original USGS MRDS record.

Maps centered on this site

Authoritative Alaska resources

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