Lost River-Cassiterite dike exogreisen

Producer in Alaska, United States with commodities Tin, Tungsten

Geologic information

Identification information

Deposit ID 10308412
Record type Site
Current site name Lost River-Cassiterite dike exogreisen

Geographic coordinates

Geographic coordinates: -167.1564, 65.47527 (WGS84)
Relative position Lost River Mine is located on Cassiterite Creek, one mile upstream of its confluence with Lost River. This confluence is 5 miles upstream from the mouth of Lost River on the Bering Sea. The Lost River Mine area includes the Cassiterite dike exogreisen deposit (TE048), the Lost River Mine skarn deposit (TE049), the Lost River Mine endogreisen deposit (TE050), and the Ida Bell dike exogreisen deposit (TE051). The Cassiterite dike exogreisen deposit crosses Cassiterite Creek about 0.9 miles upstream from its mouth (elevation approximately 300 feet). The principal surface workings in the Lost River Mine area are on the Cassiterite dike east of Cassiterite Creek between elevations of 300 and 600 feet. This is locality 8 of Cobb and Sainsbury (1972). References for this locality were summarized under the name 'Lost River' by Cobb (1975).
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Geographic areas

Country State
United States Alaska


Commodity Importance
Tin Primary
Tungsten Primary

Comments on the commodity information

  • Gangue = white mica

Materials information

Materials Type of material
Cassiterite Ore
Chalcopyrite Ore
Galena Ore
Sphalerite Ore
Stannite Ore
Wolframite Ore
Arsenopyrite Gangue
Fluorite Gangue
Kaolinite Gangue
Topaz Gangue
Tourmaline Gangue
Pyrite Gangue
Mica Gangue
Quartz Gangue


  • (Local) Greisen has extensively replaced the felsic Cassiterite dike over 2,200 feet of strike and several hundred feet of dip. Later kaolinite replacement has overprinted much of the greisen.

Mineral occurrence model information

Model code 47
USGS model code 15b
Deposit model name Sn veins
Model code 49
USGS model code 15c
Deposit model name Sn greisen

Host and associated rocks

  • Host or associated Associated
    Rock unit name Lost River
    Chronological age 80.2
    Uncertainty 2.9
    Type of media Granite
    Stratigraphic age (youngest) Late Cretaceous

Nearby scientific data

(1) -167.1564, 65.47527

Comments on the geologic information

  • Geologic Description = The pre-mineral Cassiterite dike crosscuts Ordovician limestone and dolomite above a buried and mineralized granite cupola. The dike strikes northwest, dips moderately south, and extends at depth into parts of the Lost River skarn deposit. It ranges in thickness between 3 and 21 feet but in areas of previous stoping, widths of 5 to 10 feet are common (Sainsbury, 1964, plate 10). It is extensively altered over 2,200 feet of strike in the mine area. The dike was probably emplaced along a fault and some post mineralization displacement on this structure has occurred (Sainsbury, 1964, p. 10). Originally a leucocratic and porphyritic felsic rock, the dike is extensively replaced by quartz-topaz-fluorite greisen with disseminated cassiterite and sulfide minerals such as stannite, arsenopyrite, pyrite, galena, chalcopyrite, and sphalerite. Sulfide-rich veinlets containing cassiterite crosscut the greisen in many places. Wolframite is present in greater amounts in deeper parts of the mineralized dike where its mode of occurrence is similar to that of cassiterite, including its presence in crosscutting sulfide-bearing veins. .Overprinting clay (kaolinite) alteration is common throughout the deposit. This alteration can completely obliterate preexisting textures and mineralogy, leaving only cassiterite grains in a clay matrix. Sainsbury (1964, p. 36) emphasizes that the clay alteration was superimposed on previously mineralized rock and that it did not affect tin distribution. Mining operations in the 1950's produced 309 tons of tin from 51,000 tons of ore averaging 1.13% tin (Lorain and others, 1958). Tungsten was not recovered during these operations. Some parts of the deposit were of higher grade; distinct ore shoots with greater than 2% tin were present (Hudson and Reed, 1997, p. 458). The higher grade tungsten zones contained 0.8% WO3. Sainsbury (1964, p. 50) has calculated reserves for two types of ore; 200,500 tons grading 1.3% tin and 0.125% WO3 and 105,000 tons grading 0.76% tin and 0.6% WO3. Sainsbury (1964, p. 51) suggests that the known and inferred ore with greater than 1% combined tin and WO3 could be about 430,000 tons. The deposit is open to the southeast and potential exists to the west on the other side of Cassiterite Creek.
  • Age = the age of the mineralization is assumed to be related to the development of tin systems in the Lost River area and therefore Late Cretaceous, the age of the tin-mineralizing granites there (Hudson and Arth, 1983). Fine-grained, leucocratic granite collected from a Lost River Mine dump has been dated at 80.2 +/- 2.9 my (Hudson and Arth, 1983, p.769).
  • Age = Chronological age is for Lost River Mine.

Economic information

Economic information about the deposit and operations

Development status Producer

Comments on exploration

  • Status = Active

Mining district

District name Port Clarence

Comments on the production information

  • Production Notes = Lode production from the Lost River Mine is all from the Cassiterite dike exogreisen. Production includes 5.6 tons of concentrate containing 3.5 tons of tin and 0.6 tons of tungsten in 1913 and 309 tons of tin in concentrate produced between 1952 and 1955 (Lorain and others, 1958, p. 7).

Comments on the reserve resource information

  • Reserves = Sainsbury (1964, p. 50) has calculated reserves for two types of ore; 200,500 tons grading 1.3% tin and 0.125% WO3 and 105,000 tons grading 0.76% tin and 0.6% WO3. Sainsbury (1964, p. 51) suggests that the known and inferred ore with greater than 1% combined tin and WO3 could be about 430,000 tons. The deposit is open to the southeast and potential exists to the west on the other side of Cassiterite Creek.

Comments on the workings information

  • Workings / Exploration = In addition to many surface trenches, significant underground workings exist at the Lost River Mine. Most of these are on the Cassiterite dike but some deeper exploratory drifts encountered the buried Lost River granite cupola. The underground workings include adits, drifts, declines, raises, and shafts that total several thousand feet in length (Sainsbury, 1964, plate 10). These workings are developed on five levels with over 500 feet of vertical extent and with individual drifts being up to 1,100 feet long. Many diamond drill holes have been completed from both the surface and underground.

Reference information

Links to other databases

Agency Database name Acronym Record ID Notes
USGS Alaska Resource Data File ARDF TE048

Bibliographic references

  • Deposit

    Lorain, S.H., Wells, R.R., Mihelich, Miro, Mulligan, J.J., Thorne, R.L., and Herdlick, J.A., 1958, Lode-tin mining at Lost River, Seward Peninsula, Alaska: U.S. Bureau of Mines Information Circular 7871, 76 p.

  • Deposit

    Sainsbury, C.L., 1964, Geology of the Lost River mine area, Alaska: U.S. Geological Survey Bulletin 1129, 80 p.

  • Deposit

    Cobb, E.H., and Sainsbury, C.L., 1972, Metallic mineral resource map of the Teller quadrangle, Alaska: U.S. Geological Survey Miscellaneous Field Studies Map MF-426, 1 sheet, scale 1:250,000.

  • Deposit

    Hudson, T.L., and Arth, J. G., 1983, Tin-granites of Seward Peninsula, Alaska: Geological Society of America Bulletin, v. 94, p. 768-790.

  • Deposit

    Hudson, T.L., and Reed, B.L., 1997, Tin deposits of Alaska, in Goldfarb, R.J., and Miller, L.D., eds., Mineral Deposits of Alaska: Economic Geology Monograph 9, p. 450-465.

  • Deposit

    Cobb, E.H., 1975, Summary of references to mineral occurrences (other than mineral fuels and construction materials) in the Teller quadrangle, Alaska: U.S. Geological Survey Open-File Report 75-587, 130 p.

Comments on the references

  • Primary Reference = Sainsbury, 1964

General comments

Subject category Comment text
Deposit Model Name = Exogriesen. This deposit has characteristics of both tin vein model (15b) and tin greisen model (15c) of Cox and Singer (1986).
Deposit Model Number = 15b, 15c

Reporter information

Type Date Name Affiliation Comment
Reporter 10-MAY-98 Travis L. Hudson Applied Geology