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Le Roy

Past Producer in Alaska, United States with commodities Gold, Silver, Arsenic, Cadmium, Copper, Lead, Zinc
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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 10002248
MRDS ID A013150
Record type Site
Current site name Le Roy
Alternate or previous names A. L. Parker, Pet (after about 1975)
Related records 10185346

Geographic coordinates

Geographic coordinates: -136.88101, 58.87639 (WGS84)
Relative position The mine is 0.7 mile south of the mouth of Ptarmigan Creek into Glacier Bay between Reid Inlet and Lamplugh Glacier. Veins are exposed on surface or in underground workings between about 900-1100 feet above sea level. The mine is in the N1/2 SE1/4 section 34, T. 35 S., R. 51 E., of the Copper River Meridian. The location coordinates are of the main Le Roy vein. Location is accurate within 0.1 mile. The mine is location 17 of Cobb (1972, MF-436).

Site location context

Political divisions (FIPS codes)

Hoonah-Angoon(Census area)

Alaska(state)

United States(country)

North America(continent)

Land(continent)

USGS map quadrangles

Mount Fairweather D-3(quadrangle 1:63,360 scale)

Mount Fairweather NE(quadrangle 1:100,000 scale)

Mount Fairweather(quadrangle 1:250,000 scale)

Hydrologic units (watersheds)

Glacier Bay(hydrologic unit)

Northern Southeast Alaska(hydrologic accounting unit)

Southeast Alaska(hydrologic subregion)

Alaska(hydrologic region)

Federal lands

Glacier Bay National Park(National Park)

National Park NPS(Type of land area)

NPS(Federal land areas administered by NPS)

Geographic areas

Country State
United States Alaska

Commodities

Commodity Importance
Gold Primary
Silver Secondary
Arsenic Critical Secondary
Cadmium Secondary
Copper Secondary
Lead Secondary
Zinc Critical Secondary

Comments on the commodity information

  • Ore Material = Gold (native)
  • Ore Material = Silver (native)

Materials information

Materials Type of material
Arsenopyrite Ore
Chalcopyrite Ore
Galena Ore
Pyrite Ore
Sphalerite Ore
Gold Ore
Silver Ore
Ankerite Gangue
Quartz Gangue

Alteration

  • (Local) Rossman (1959, B 1058-B. p. 43) notes intense alteration that locally extends to 10 or 15 feet on each side of the vein, and is marked on the surface by rust-red staining. Alteration products almost certainly include ankerite and chlorite.

Mineral occurrence model information

Model code 273
USGS model code 36a
Deposit model name Low-sulfide Au-quartz vein
Mark3 model number 27

Host and associated rocks

  • Host or associated Host
    Rock type
    Stratigraphic age (youngest) Cretaceous

Nearby scientific data

(1) -136.88101, 58.87639
ListMap

Economic information

Comments on the geologic information

  • Geologic Description = The LeRoy mine is within a large sheared roof pendant within a granodiorite pluton of Cretaceous age (Brew and others, 1978). The pendant, strikes northerly to north-northeast in the vicinity of the mine; to the south, strike is north-northwest. Rocks within the pendant include graphitic schist and crystalline schist that Rossman (1959, B 1058-B, p. 45) proposed was metasedimentary. Thin section studies by MacKevett and others (1971, p. 56) show, however, that much of the schistose crystalline rock is intensely sheared (cataclastic) granodiorite. South of the mine a major fault lies within and is subparallel to the cataclastic zone (Rossman, 1959, B 1058-B, pl. 4). This fault is locally mineralized, as at the Highland Chief (MF030). A mafic dike that strikes northeast crops out east of mine; it appears to form the vein wall rock in the south part of the mine. ? the LeRoy vein is the thickest and most continuous of a swarm of about 15 quartz veins exposed at the mine. The veins strike north-northeast and are almost vertical. At least two other veins may have had some gold production; one is a vein developed in a short drift 25 feet east of the main workings. The so-called Pet vein was developed in a subparallel drift 100 feet northwest of the main LeRoy workings. ? the LeRoy vein consisted mainly of quartz and ankerite and averaged about 2 feet thick. Locally it was as much as 4.5 feet thick. The veins of the area are banded. Typically they contain 3-5 percent, occasionally more, sulfide minerals, which in approximate order of abundance are, arsenopyrite, pyrite, sphalerite, galena, and chalcopyrite. Gold occurred both in relatively coarse native form, also finely divided within the sulfide minerals. About one-third of the gold was recovered at the mine as native gold in gravity circuit or on amalgam plates. The rest was recovered from sulfide concentrate shipped to the smelter at Tacoma. The mine was rich, averaging about 3 ounces of gold per ton. Vein material exposed in the floor of the lower LeRoy workings averages about 1.25 ounce per ton gold in a remaining unmined shoot (Holdsworth, 1955). The vein appears to terminate or lose strength in the mafic dike host, but the vein system has not been well explored to the south.
  • Age = The granodiorite host rock is Cretaceous in age; mineralization is inferred to be Late Cretaceous or younger.
  • Age = Host rock is Cretaceous.

Economic information about the deposit and operations

Development status Past Producer
Commodity type Metallic

Comments on exploration

  • Status = Inactive

Mining district

District name Juneau

Comments on the production information

  • Production Notes = Production was estimated by the U.S. Bureau of Mines (Kimball and others, 1978) to be from $130-170 thousand with gold at $35.00/ounce, or about 3700-4900 ounces of gold. During the main period of mining, the ore was crushed and ground in a mill on site. The ground ore was tabled; the dense table cut was amalgamated. The low-density table cut was then treated by flotation. The flotation concentrate was shipped to a smelter, presumably at Tacoma. The grinding limits are not known, so it is not possible to tell how much gold would have been liberated with very fine grinding. The owners reported only about 25 percent of the ore as free-milling (Kimball and others, 1978, p. C203). the main period of mining was from 1941-45 (Twenhofel and others, 1949, p. 32-34; Rossman, 1959, B 1058-B. p. 38-39).

Comments on the reserve resource information

  • Reserves = Only a very small reserve is indicated with the present data. There are only about 260 ounces indicated in the floor of the lower adit by assuming 50 x 25 x 2-feet, a tonnage factor of 12 cu-ft/ton and grade of 1.25 oz/ton based on sampling reported by Holdsworth (1955).? Several narrow quartz veins are rich; the potential for discovering at least as much ore as was produced is good.

Comments on the workings information

  • Workings / Exploration = The discovery of the LeRoy occurred rather late in the history of the district. It was found in 1938 by A. L. Parker and his son, Leslie F. Parker. The Parkers mined and milled the ore on a small scale until Mr. Parker's death in 1941 (Rossman, 1959, B 1058-B, p. 38). The most extensive mining was done on lease between 1941 and 1945 by the LeRoy Mining Co. ? the LeRoy vein system has been explored by three main adits with more than 600 feet of workings. The upper LeRoy level is at a reported elevation of 987 feet; the lower LeRoy level is at about 950 feet. The workings on the Pet vein are at about 950 feet. The LeRoy vein was stoped above the upper Leroy level for about 100 feet. The vein was stoped below that level, but It has not been developed below the lower Leroy level. A 2-foot wide zone in the floor of the Lower level is reported to average 1.25 oz/ton gold for a distance of 50-feet.? the Pet vein is narrower. As exposed it generally ranges from 3-8 inches in thickness. It is about 1.5 feet thick in the face of the Pet drift. Most samples are in the 0.01 to .01 oz/ton gold range, but MacKevett obtained 0.44 ounce per ton gold on a narrow north-striking vein near the portal of the tunnel, and the Territorial Dept. of Mines found 0.22 ounce per ton gold in a raise near the face of the Pet. (MacKevett and others, 1971, p. 56-59, Pl. 9) the Pet probably was drilled in the 1970s, but the location of drill logs is unknown. ? the Leroy mine was examined by several territorial engineers, including Roehm (1942), Fowler (1950) and Holdsworth (1955).

Reference information

Bibliographic references

Comments on the references

  • Primary Reference = Rossman, 1959 (B 1058-B); Kimball and others, 1978

General comments

Subject category Comment text
Deposit Model Name = Similar to low-sulfide gold-quartz vein (Cox and Singer, 1986; model 36a). Low-sulfide gold-quartz vein, grading into a medium-sulfide type.
Deposit Other Comments = There was minor activity at the LeRoy (Pet) in the 1970s by Jeannie Trump, the daughter of A. L Parker, and associates. Reportedly mineralization was sufficiently good to uphold the validity of two unpatented claims. The deposit is in Glacier Bay National Park and Preserve and the property is believed to be inactive.? the LeRoy deposit was the most productive mine in the Reid Inlet gold area, as defined by Kimball and others, 1978).

Reporter information

Type Date Name Affiliation Comment
Reporter 06-APR-99 Hawley, C.C. 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.