Terra Cotta Mountains

Occurrence in Alaska, United States with commodities Silver, Gold, Copper, Lead, Antimony

Geologic information

Identification information

Deposit ID 10307755
Record type Site
Current site name Terra Cotta Mountains

Geographic coordinates

Geographic coordinates: -153.509, 61.94088 (WGS84)
Relative position This occurrence is on a ridge in the Terra Cotta Mountains, east of upper Post River. It is on the north flank of peak 5830, at an elevation of about 5,400 feet. The map site is in the NW1/4 section 4, T 21 N, R 23 W, of the Seward Meridian. This occurrence is sample locations 809 and 810 of Allen (1990); Allen and others (1990), and Allen and Slaughter (1990).
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Geographic areas

Country State
United States Alaska


Commodity Importance
Silver Primary
Gold Primary
Copper Primary
Lead Primary
Antimony Primary

Comments on the commodity information

  • Gangue = Carbonate

Materials information

Materials Type of material
Arsenopyrite Ore
Chalcopyrite Ore
Pyrite Ore
Pyrrhotite Ore
Stibnite Ore
Quartz Gangue


  • (Local) Silicification.

Mineral occurrence model information

Model code 85
USGS model code 22c
Deposit model name Polymetallic veins
Mark3 model number 46

Nearby scientific data

(1) -153.509, 61.94088

Comments on the geologic information

  • Geologic Description = Quartz-carbonate breccia veins are developed in altered granitic rocks and nearby graywacke country rock. The veins commonly contain pyrite, arsenopyrite, lesser stibnite and chalcopyrite, and some pyrrhotite. Allen and others (1990, samples 805 to 814) collected several samples in the general area of this locality. These samples contain as much as 1 ppm gold, 100 ppm silver, 1,000 ppm barium, 300 ppm bismuth, 1,000 ppm cobalt, 7,000 ppm copper, 20,000 ppm lead, 1,500 ppm antimony, and 500 ppm tin and greater than 10,000 ppm arsenic, 2,000 ppm boron, and 5,000 ppm manganese. The sedimentary rocks are Jurassic or Lower Cretaceous, and the Upper Cretaceous or Tertiary granitic rocks are part of the Alaska-Aleutian Range batholith (Reed and Lanphere, 1973; Nokleberg and others, 1994).
  • Age = Late Cretaceous or Tertiary. The veins crosscut Upper Cretaceous or Tertiary granitic rocks of the Alaska-Aleutian Range batholith.

Economic information

Economic information about the deposit and operations

Development status Occurrence

Comments on exploration

  • Status = Inactive

Mining district

District name McGrath

Comments on the workings information

  • Workings / Exploration = Surface observation and sampling has occurred at this locality.

Reference information

Links to other databases

Agency Database name Acronym Record ID Notes
USGS Alaska Resource Data File ARDF LH008

Bibliographic references

  • Deposit

    Reed, B. L., and Lanphere, M. A., 1973, Alaska-Aleutian Range batholith-- Geochronology, chemistry, and relation to circum-Pacific plutonism: Geological Society of America Bulletin, v. 84, no. 8, p. 2583-2610.

  • Deposit

    Nokleberg, W.J., and others, 1994, Metallogeny and major mineral deposits of Alaska and Metallogenic map of significant metalliferous lode deposits and placer districts of Alaska, in Plafker, G. and Berg, H.C., eds., The Geology of Alaska: Boulder, Colorado, Geological Society of America: The Geology of North America, v. G1, p. 855-904 and v. G1, Plate 11, scale 1:2,500,000.

  • Deposit

    Allen, M.S, 1990, Gold anomalies and newly identified gold occurrences in the Lime Hills quadrangle, Alaska , and their association with the Hartman sequence plutons, in Goldfarb, R. J., Nash, J. T., and Stoeser, J. W., eds., Geochemical studies in Alaska by the U.S. Geological Survey, 1989: U.S. Geological Survey Bulletin 1950, p. F1-F16.

  • Deposit

    Allen, M. S., Malcolm, M. J., Motooka, J. M., and Slaughter, K. E., 1990, Geologic description, chemical analyses, and sample locality map for rock samples collected from the eastern part of the Lime Hills quadrangle, Alaska: U.S. Geological Survey Open-File Report 90-69, 49 p..

  • Deposit

    Allen, M.S., and Slaughter, K. E., 1990, Mineralogical data and sample locality map of nonmagnetic, heavy-mineral-concentrate samples collected from the eastern part of the Lime Hills quadrangle, Alaska: U.S. Geological Survey Open-File Report 90-67, 64 p., 1 plate, scale 1:250,000.

Comments on the references

  • Primary Reference = Allen, 199o

General comments

Subject category Comment text
Deposit Model Name = Polymetallic veins (Cox and Singer, 1986, model 22c)

Reporter information

Type Date Name Affiliation Comment
Reporter 10-JUN-01 Travis L. Hudson Applied Geology
Reporter 10-JUN-01 Madelyn A. Millholland Millholland & Associates