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Eva

Prospect in Alaska, United States with commodities Copper, Silver, Gold
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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. Nearby scientific data
  10. Economic information about the deposit and operations
  11. Mining district
  12. Links to other databases
  13. Bibliographic references
  14. General comments
  15. Reporter information

Geologic information

Identification information

Deposit ID 10308542
Record type Site
Current site name Eva

Geographic coordinates

Geographic coordinates: -149.41334, 67.64971 (WGS84)
Relative position The Eva prospect is at an elevation of about 4,500 feet in the hills between Big Spruce Creek and Mathews River (NW1/4 sec. 32, T. 33 N., R. 8 W., of the Fairbanks Meridian). It is approximately 10 miles north of the Big Lake (site) and 1 mile northwest of the Victor prospect (CH064). The Eva prospect was part of a larger claim group that also encompassed the Victor and Venus (CH065) prospects. The location is accurate within a 1/2-mile radius.

Site location context

Political divisions (FIPS codes)

Yukon-Koyukuk(Census area)

Alaska(state)

United States(country)

North America(continent)

Land(continent)

USGS map quadrangles

Chandalar C-5(quadrangle 1:63,360 scale)

Chandalar N(quadrangle 1:100,000 scale)

Chandalar(quadrangle 1:250,000 scale)

Hydrologic units (watersheds)

Alaska(hydrologic region)

Federal lands

Doyon, Limited(ANCSA Region)

ANCSA Region NTVPIC(Type of land area)

NTVPIC(Federal land areas administered by NTVPIC)

Geographic areas

Country State
United States Alaska

Commodities

Commodity Importance
Copper Primary
Silver Secondary
Gold Secondary

Materials information

Materials Type of material
Chalcopyrite Ore
Magnetite Ore
Pyrite Ore

Alteration

  • Propylitic and sericitic alteration of the meta-granodiorite and retrograde epidote/actinolite alteration of the skarns.

Mineral occurrence model information

Model code 58
USGS model code 18a
Deposit model name Porphyry Cu, skarn-related
Mark3 model number 9

Nearby scientific data

(1) -149.41334, 67.64971
ListMap

Economic information

Comments on the geologic information

  • Geologic Description = The Eva prospect is one of several Cu skarn deposits in the Chandalar area which have been described in general by Newberry and others (1986). They are all northwest of a belt of Devonian(?) granitic rocks informally named the Horace Mountain plutons. Many of these Cu skarns exhibit both prograde garnet and pyroxene and retrograde epidote and actinolite mineral assemblages. Newberry and others (1986) stated that the mineralogy, mineralization, and alteration of these skarns tend to place them in the category of continental-margin, porphyry-related copper skarns. Published descriptions of individual prospects in this group are scarce. Some of the descriptions of the Eva prospect include it with the nearby Victor and Venus prospects (DeYoung, 1978; Cobb and Cruz, 1983). The Venus prospect in particular is characterized by porphyry-related mineralization, and the Eva prospect thus has been characterized as a porphyry copper and (or) copper skarn deposit (Cobb and Cruz, 1983). Newberry and others (1986), however, classified it as a Cu skarn. Dillon (1996) mapped the prospect area principally as Devonian hornblende granodiorite gneiss of the Horace Mountain pluton and contact-related tactite and calcareous hornfels. Outcrop areas of pyritized meta-granodiorite intrusives near the Eva prospect are smaller than those at either the nearby Victor or Venus prospects. The limited information available suggests that the principal deposit at the Eva prospect is a copper-bearing garnet and pyroxene skarn. Unlike the Venus prospect, there is little evidence at the Eva prospect that suggests appreciable copper mineralization in the intrusive rocks. Although the distribution of copper in the meta-igneous rocks and the related skarns is unclear, the available published information suggests that copper is more abundant in the skarns. Nicholson (1990) noted that some workers have characterized the mineralization in the Big Spruce Creek area as volcanogenic in origin, although this model is not widely accepted.
  • Age = Devonian based on reported Early Devonian Pb/Pb zircon ages from the associated Baby Creek batholith and Horace Mountain plutons (Dillon and others, 1996).

Economic information about the deposit and operations

Development status Prospect
Commodity type Metallic

Comments on exploration

  • Status = Not determined

Mining district

District name Koyukuk

Comments on the workings information

  • Workings / Exploration = Surface sampling only.

Reference information

Bibliographic references

Comments on the references

  • Primary Reference = Nicholson, 1990

General comments

Subject category Comment text
Deposit Model Name = Porphyry Cu, skarn-related deposits (Cox and Singer, 1986; model 18a)
Deposit Other Comments = See also: Victor (CH064), Venus (CH065), and Evelyn Lee (CH059). Much of the published information on the Eva prospect is combined with descriptions of the Venus and Victor prospects. The land (and presumably the original claims) have been acquired by Doyon, Limited via its Alaska Native Claims Settlement Act selections. Bornite and chalcopyrite sightings have been reported in cliffs along Mathews River (DeYoung, 1978, loc. 72). They may be related to the Eva prospect.

Reporter information

Type Date Name Affiliation Comment
Reporter 17-NOV-1999 J.M. Britton U.S. Geological Survey

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.