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Unnamed (at head of Rulby Creek)

Occurrence in Alaska, United States with commodity Iron
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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. Nearby scientific data
  9. Economic information about the deposit and operations
  10. Mining district
  11. Links to other databases
  12. Bibliographic references
  13. General comments
  14. Reporter information

Geologic information

Identification information

Deposit ID 10307910
Record type Site
Current site name Unnamed (at head of Rulby Creek)

Geographic coordinates

Geographic coordinates: -165.7404, 64.77168 (WGS84)
Relative position This occurrence is about 0.8 mile south of the Tub Mountain prospect (NM018) near the head of Rulby Creek (NM016). The occurrence is at an elevation of 760 feet and is accurately located from Herreid (1970).

Site location context

Political divisions (FIPS codes)

Nome(Census area)

Alaska(state)

United States(country)

North America(continent)

Land(continent)

USGS map quadrangles

Nome D-2(quadrangle 1:63,360 scale)

Solomon NW(quadrangle 1:100,000 scale)

Nome(quadrangle 1:250,000 scale)

Hydrologic units (watersheds)

Nome(hydrologic unit)

Norton Sound(hydrologic accounting unit)

Northwest(hydrologic subregion)

Alaska(hydrologic region)

Geographic areas

Country State
United States Alaska

Commodities

Commodity Importance
Iron Primary

Materials information

Materials Type of material
Limonite Ore

Alteration

  • (Local) Dolomitization and oxidation.

Nearby scientific data

(1) -165.7404, 64.77168
ListMap

Economic information

Comments on the geologic information

  • Geologic Description = This limonite occurrence is about 0.8 mile south of the Tub Mountain prospect (NM018). It is a few hundred feet across (Herreid, 1970) and one of several carbonate-hosted, iron-rich deposits in the area (NM014, NM014, NM017, NM018, and NM020). The limonite can be massive to granular, botryoidal, mamillary, or fibrous. The iron content ranges to as much as 59 percent in analyzed samples (Eakin, 1915 [B 622-I, p. 361-365]). Hematite, pyrolusite, and calcite are present locally. This occurrence and other iron deposits of the Sinuk River area are at or near the base of massive marble whose protolith age is probably lower Paleozoic (Sainsbury, Hummel, and Hudson, 1972; Bundtzen and others, 1994). The deposits are locally controlled by high-angle faults or folds, but they are in general crudely stratabound within the basal massive marble or underlying calc-schist (Mulligan and Hess, 1965; Herreid, 1970). This stratigraphic interval also hosts base metal sulfide-fluorite-barite deposits at the Galena (NM130) and Quarry prospects (NM135). The origin and age of the iron deposits of the Sinuk River area are uncertain. The deposits may be, in part, gossan developed on oxidized sulfide deposits (Eakin, 1915 [B 622-I, p. 361-365]; Mertie,1918 [B 662-I, p. 425-449]; Cathcart, 1922; Mulligan and Hess, 1965; Herreid, 1970). Several of the iron deposits, including American (NM014) and Monarch (NM017), are locally highly anomalous in zinc and lead. Arguing against a simple gossan origin is the paucity of diagnostic textures and structures in boxworks that would suggest derivation from specific sulfide minerals. Alternatively, these deposits could be hypogene iron oxide and carbonate deposits that are transitional to lead-zinc-barite deposits such as the Quarry (NM135). The age of the iron deposits of the Sinuk River area is most likely post-mid-Cretaceous because faults that crosscut mid-Cretaceous metamorphic rocks are an important control on them. A Late Cretaceous age for the iron deposits was suggested by Brobst and others (1971) because this is the age of fluorine-rich tin granites of northwestern Seward Peninsula (Hudson and Arth, 1983). The youngest possible age appears to be Early Tertiary, when deep weathering, sandstone-type uranium mineralization, and possibly karst formation occurred to the east in the Solomon quadrangle (Hudson, 1999).
  • Age = Late Cretaceous or Early Tertiary; post mid-Cretaceous metamorphism.

Economic information about the deposit and operations

Development status Occurrence

Comments on exploration

  • Status = Probably inactive

Mining district

District name Nome

Comments on the workings information

  • Workings / Exploration = There may be small prospecting pits at this locality.

Reference information

Bibliographic references

Comments on the references

  • Primary Reference = Herreid, 1970

General comments

Subject category Comment text
Deposit Model Name = Carbonate-hosted, iron oxide deposit.

Reporter information

Type Date Name Affiliation Comment
Reporter 22-OCT-99 Hawley, C.C. and Hudson, Travis L. Hawley Resource Group

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.