Mirror Harbor Copper-Nickel Prospect

Occurrence in Alaska, United States with commodities Nickel, Copper
Sections on this page
  1. Identification information
  2. Geographic coordinates
  3. Site location context
  4. Geographic areas
  5. Commodities
  6. Materials information
  7. Host and associated rocks
  8. Nearby scientific data
  9. Ore body information
  10. Controls for ore emplacement
  11. Economic information about the deposit and operations
  12. Mining district
  13. Land status
  14. Reserves and resources
  15. Workings at the site
  16. Links to other databases
  17. Bibliographic references
  18. General comments
  19. Reporter information

Geologic information

Identification information

Deposit ID 10002338
MRDS ID A013252
Record type Site
Current site name Mirror Harbor Copper-Nickel Prospect
Related records 10258629

Geographic coordinates

Geographic coordinates: -136.32093, 57.79443 (WGS84)
Elevation 3
Relative position ON NORTH TIP OF FLEMING ISLAND.

Site location context

Political divisions (FIPS codes)

Sitka(Borough)

Alaska(state)

United States(country)

North America(continent)

Land(continent)

USGS map quadrangles

Sitka D-7(quadrangle 1:63,360 scale)

Sitka NW(quadrangle 1:100,000 scale)

Sitka W OE(quadrangle 1:250,000 scale)

Hydrologic units (watersheds)

Central Southeast Alaska(hydrologic accounting unit)

Southeast Alaska(hydrologic subregion)

Alaska(hydrologic region)

Federal lands

National Forest(land status)

Geographic areas

Country State
United States Alaska

Comments on the location information

  • USGS B 947-C, PL. 15, 16; USGS MF-467, LOC. 16. LOCATION AT SHAFT. LAND STATUS VALUE CALCULATED 6-94 USING GIS OVERLAY ANALYSIS WITH BLM 1:2,500,000 SCALE OWNERSHIP STATUS MAP (1991).

Commodities

Commodity Importance
Nickel Critical Primary
Copper Primary

Materials information

Materials Type of material
Chalcopyrite Ore
Niccolite Ore
Pentlandite Ore
Pyrrhotite Ore
Plagioclase Gangue
Pyroxene Gangue

Analytical data

Result AVERAGE OF 37 FT. OF ORE SAMPLES AT 75 FT. LEVEL DRIFT TAKEN IN 1917 IS 3.42% NI AND 1.58% CU, WITH MAXIMUM VALUES OF 5.70% NI AND 4.00% CU, ACCORDING TO USGS B 947-C, TABLE 17, NOS. 4-17. INDICATED AVERAGE GRADE OF DEPOSIT FROM DIAMOND DRILL HOLE CORES AND CHANNEL SAMPLES BY USBM IN 1942 IS 1.54% NI AND 0.78% CU, ACCORDING TO USGS B 947-C, P. 62.

Host and associated rocks

  • Host or associated Associated
    Rock type Plutonic Rock > Mafic Intrusive Rock > Diorite
    Stratigraphic age (youngest) Late Cretaceous
  • Host or associated Associated
    Rock type Plutonic Rock > Mafic Intrusive Rock > Gabbro > Norite
  • Host or associated Host
    Rock type Plutonic Rock > Mafic Intrusive Rock > Gabbro > Norite

Nearby scientific data

(1) Kkbm

Economic information

Ore body information

  • General form POD
    Plunge direction 75 DEGREES SE
    Thickness 33.53M
    Length 12.19M
    Width 6.1M
    Depth to top 0M
    Depth to bottom 53.34M

Controls for ore emplacement

  • Cut Off By Fault Striking N 80 Degrees E, Dipping 75 Degrees N

Comments on the geologic information

  • NORITE BODY IS PART OF COMPOSITE STOCK INTRUDED INTO METAMORPHOSED GRAYWACKE AND GREENSTONE. NORITE IS IN CONTACT WITH DIORITE.

Economic information about the deposit and operations

Development status Occurrence
Commodity type Metallic
Deposit size Small
Significant No
Discovery year 1911

Mining district

District name Chichagof

Land status

Ownership category National Forest

Reserves and resources

  • Type In-situ
    Estimate year 1946
    Commodity Subtype Grade units Group Importance Year
    Nickel Ni 1.54 wt-pct Nickel Major 1946
    Copper Cu 0.78 wt-pct Copper Major 1946

Comments on the reserve resource information

  • GRADE IS AVERAGE OF 72.5 FT. OF DIAMOND DRILL HOLE CORE AND 29 FT. OF SURFACE CHANNEL SAMPLE. AVERAGE GRADE OF CORE ALONE IS 1.57% NI AND 0.88% CU.

Workings at the site

  • Type of workings Surface
    Area 0.007HA
    Length 100.58M
    Overall depth 53.34M
    Overall length 12.19M
    Overall width 6.1M

Comments on the workings information

  • 175 FT. SHAFT WITH 155 FT. OF DRIFTS AT 75 FT. AND 175 FT. LEVELS. SHAFT FLOODED AS OF 1942. 5 DIAMOND DRILL HOLES DRILLED BY USBM IN 1942, AS WELL AS SURFACE TRENCHES.

Comments on development

  • CLAIMS STAKED 1911, RELOCATED 1915. 180 FT. SHAFT SUNK IN 1917 BY ALASKA NICKEL MINES. EXTENSIVE DRILLING AND TRENCHING BY USBM IN 1942. NUMEROUS ACTIVE CLAIMS AS OF 1977-USBM OFR 20-73

Reference information

Bibliographic references

  • Deposit

    USGS B 947-C, P. 56-63, PLATES 15, 16 (1946)

  • Deposit

    USGS B 936-I, P. 221-243 (1942)

  • Deposit

    USGS MF-467, LOC. 16 (1972)

  • Deposit

    USGS OF 78-450, P. 82-84 (1978)

  • Deposit

    USBM OFR 20-73, LOC. 153B (1978)

  • Other Database

    BAG-B-947-C-PL-15, 16

General comments

Subject category Comment text
Deposit MAGMATIC SEGREGATIONS OF PYRRHOTITE, PENTLANDITE, CHALCOPYRITE, AND MINOR NICCOLITE OCCUR LARGELY AS SMALL PODS (UP TO 4 IN. BY 4 IN. BY 8 IN.) IN NEARLY BARREN NORITE BODY. NORITE ALSO CONTAINS LOW-GRADE DISSEMINATIONS OF SULFIDES. NORITE IS PART OF COMPOSITE STOCK AND IS IN CONTACT WITH DIORITE. SULFIDE-BEARING PORTION OF NORITE IS 40 FT. LONG AND 20 FT. WIDE AT SURFACE, AND EXTENDS TO AVERAGE DEPTH OF 110 FT. WHERE IT IS CUT OFF BY N 80 DEGREES E STRIKING, 75 DEGREES N DIPPING FAULT. MASSIVE SULFIDE-BEARING ORE IS FOUND AT THE 175 FT. LEVEL DRIFT IN SHAFT. DEPOSIT FORMS PIPE-SHAPED BODY PLUNGING 75 DEGREES SE, AND IS SURROUNDED BY BARREN NORITE NEAR DIORITE CONTACT.
Deposit LUMPED INTO SAME DEPOSIT AS SI-17 AND SI-18 (DAVISON BAY) BY COBB IN MF-467, LOC. 16 AND OF 78-450, P. 82-84. NO PRODUCTION RECORDED, ALTHOUGH CONSIDERABLE AMOUNT OF ORE WAS MINED. ; INFO.SRC : 1 PUB LIT
Deposit THIS SITE NAME WAS CREATED BY THE REPORTER OR OTHER USGS EMPLOYEE BASED ON PROXIMITY TO SOME MAJOR GEOGRAPHIC FEATURE.

Reporter information

Type Date Name Affiliation Comment
Reporter 01-MAY-1987 Leonard, Kenneth R. (Huber, Donald F.) U.S. Geological Survey

Beyond USGS

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

Authoritative Alaska resources

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