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Lost River-endogreisen

Producer in Alaska, United States with commodities Tin, Silver, Copper, Lead, Zinc, Tungsten
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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 10308414
Record type Site
Current site name Lost River-endogreisen

Geographic coordinates

Geographic coordinates: -167.1594, 65.47327 (WGS84)
Relative position 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 Lost River endogreisen deposit is located in a subsurface granite cupola below the Lost River skarn deposit. The skarn is exposed along and east of Cassiterite Creek at elevations of 275 to 400 feet about 0.9 miles upstream from the creek's confluence with Lost River. The upper part of the endogreisen is within 100 to 200 feet of the surface whereas deeper parts extend to depths of 750 feet or more. This deposit was included as part of locality 8 by Cobb and Sainsbury (1972). References were summarized under the name 'Lost River' by Cobb (1975).

Site location context

Political divisions (FIPS codes)

Nome(Census area)

Alaska(state)

United States(country)

North America(continent)

Land(continent)

USGS map quadrangles

Teller B-5(quadrangle 1:63,360 scale)

Teller SE(quadrangle 1:100,000 scale)

Teller(quadrangle 1:250,000 scale)

Hydrologic units (watersheds)

Imuruk Basin(hydrologic unit)

Norton Sound(hydrologic accounting unit)

Northwest(hydrologic subregion)

Alaska(hydrologic region)

Geographic areas

Country State
United States Alaska

Commodities

Commodity Importance
Tin Critical Primary
Silver Secondary
Copper Secondary
Lead Secondary
Zinc Critical Secondary
Tungsten Critical Secondary

Comments on the commodity information

  • Gangue = white mica

Materials information

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

Alteration

  • (Local) There is a well-developed quartz-tourmaline-fluorite greisen at depth, a mica-rich greisen in the roof zone, and both mica- and clay-matix hydrothermal breccias above the roof zone. The greisen types appear to merge with one another and the breccias are late, overprinting assemblages.

Mineral occurrence model information

Model code 49
USGS model code 15c
Deposit model name Sn greisen

Host and associated rocks

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

Nearby scientific data

(1) -167.1594, 65.47327
ListMap

Economic information

Comments on the geologic information

  • Geologic Description = The Lost River endogreisen deposit is developed at the roof of a highly differentiated, fine-grained granite cupola and in sheeted zones at depth within the cupola. The Lost River skarn deposit is developed in Ordovician limestone country rocks adjacent to and above the endogreisen deposit. Late hydrothermal breccia, with mica- and clay-rich matrices, have been superimposed on both endogreisen and skarn (Dobson, 1982, figure 4). 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). As described by Dobson (1982), the roof greisen is mica-rich, commonly 30 to 60% muscovite and probably zinnwaldite. The mica-rich greisen merges upward with hydrothermal breccias having a mica-rich matrix. Downward the mica-rich roof greisen gives way to quartz-rich greisen that characteristically contains tourmaline and sulfide minerals including pyrite, arsenopyrite, galena, sphalerite, and chalcopyrite. There are gradations from unaltered to completely greisenized granite but in places only thin, quartz-arsenopyrite, quartz-tourmaline, and greisen veins are present in granite. The roof greisen as mapped by Dobson (1982, figures 4 and 5), has dimensions of about 120 x 400 x 1,000 feet. Sainsbury's (1964, plate 9) compilation of grade data for this part of the deposit indicates that the general grade is a few tenths of a percent tin and a few hundreths of a percent WO3. . The deeper sheeted greisen was defined by Dobson (1982, figure 4) but it is primarily known from intercepts in two diamond drill holes completed by Teasgulf Inc. in 1979. Hole TG 2 (collared at 275 feet elevation, azimuth of N 19 E, inclined at 67.5 degrees, and a total depth of 1,012 feet) encountered: (1) 0.19% tin, 0.74% copper, 0.95% lead, 4.32% zinc, 2.73 opt silver, and 0.01% WO3 from 633 to 638 feet; (2) 1.21% tin, 0.05% copper, 0.06% lead, 0.03% zinc, 0.18 opt silver, and 0.06% WO3 from 638 to 647 feet; (3) 0.84% tin, less than 0.03% copper, 0.18% lead, 0.43% zinc, 0.27 opt silver, and 0.01% WO3 from 800.1 to 814.5 feet; and (4) 1.33% tin, less than 0.03% copper, less than 0.04% lead and zinc, 0.04 opt silver, and 0.05% WO3 from 814.5 to 823.6 feet. Hole TG 3 (collared at 321 feet elevation, azimuth of N 19 E, inclined at 64.5 degrees, and a total depth of 1,037 feet) encountered: (1) 0.28% tin, 0.08% copper, 0.78% lead, 0.80% zinc, and 1.75 opt silver (tungsten was not determined) from 778.5 to 789.8 feet; and (2) 0.88% tin, 0.08% copper, 0.20% lead, 2.13% zinc, and greater than 3.4 opt silver (tungsten was not determined) from 796.3 to 801.4 feet. Other zones of weaker tin metallization and weaker to stronger base metal and silver metallization are present in these holes. The metallization is in highly silicified zones with sulfide minerals, tourmaline, and fluorite in granite.
  • 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 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 = Production from the Lost River Mine has been from the Cassiterite dike exogreisen deposit (TE048).

Comments on the reserve resource information

  • Reserves = Resource estimates have not been separately determined for the endogreisen deposits; grades are commonly a few tenths percent tin and a few hundreths percent WO3 although some greisen sheets at depth have higher tin grades, base metals, and silver in places.

Comments on the workings information

  • Workings / Exploration = This prospect has been explored by 750 feet of underground workings of the Lost River mine (32 and 195 crosscuts, Calcite drift, and 190 raise; Sainsbury, 1964, plate 9). The upper roof greisen has been encountered by many USBM and Lost River Mining Corporation drill holes and the deeper sheeted greisen zones hve been encountered by two Texasgulf Inc diamond drill holes.

Reference information

Bibliographic references

Comments on the references

  • Primary Reference = Texasgulf, Inc., 1979; Dobson, 1982

General comments

Subject category Comment text
Deposit Model Name = Endogreisen including roof and sheeted greisen. Tin greisen model (15c) of Cox and Singer, 1986).

Reporter information

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

Beyond USGS

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

Maps centered on this site

Authoritative Alaska resources

These are landing pages for further research — the state agencies don't currently expose per-mine deep links.