1. Mineral Resources
  2. Online Spatial Data
  3. Mineral Resource Data System (MRDS)

Mary T.

Prospect in Alaska, United States with commodities Gold, Copper
Map
XML
JSON
KML
C
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 10001563
MRDS ID A012311
Record type Site
Current site name Mary T.
Related records 10112720

Geographic coordinates

Geographic coordinates: -131.9729, 55.59863 (WGS84)
Relative position The Mary T. prospect is at an elevation of about 250 feet, 0.3 mile northeast of the head of the falls at the mouth of Falls Creek. The site is in section 30, T. 72 S., R. 88 E., of the Copper River Meridian. It corresponds to loc. 257 in Maas and others (1995, fig. 46), and to loc. 36 in Elliott and others (1978). The location is accurate within 0.1 mile.

Site location context

Political divisions (FIPS codes)

Prince of Wales-Hyder(Census area)

Alaska(state)

United States(country)

North America(continent)

Land(continent)

USGS map quadrangles

Ketchikan C-6(quadrangle 1:63,360 scale)

Ketchikan NW(quadrangle 1:100,000 scale)

Ketchikan(quadrangle 1:250,000 scale)

Hydrologic units (watersheds)

Southern Southeast Alaska(hydrologic accounting unit)

Southeast Alaska(hydrologic subregion)

Alaska(hydrologic region)

Federal lands

Tongass National Forest(National Forest)

National Forest FS(Type of land area)

FS(Federal land areas administered by FS)

Geographic areas

Country State
United States Alaska

Commodities

Commodity Importance
Gold Primary
Copper Secondary

Materials information

Materials Type of material
Chalcopyrite Ore
Gold Ore
Pyrite Ore
Quartz Gangue

Alteration

  • (Local) The hostrocks are pyritized, and the chalcopyrite locally is oxidized to malachite and azurite.

Mineral occurrence model information

Model code 75
USGS model code 19c
Deposit model name Distal disseminated Ag-Au
Mark3 model number 18

Host and associated rocks

  • Host or associated Host
    Rock type Metamorphic Rock > Schist

Nearby scientific data

(1) -131.9729, 55.59863
ListMap

Economic information

Comments on the geologic information

  • Geologic Description = The country rocks near this site include gray and green phyllite and semischist derived from intertonguing flysch and andesitic and basaltic volcanic rocks (Berg and others, 1988, p. 17-20); and gray felsic schist possibly derived from silicic tuff (Maas and others, 1995, p. 183 and fig. 46). Near Smugglers Cove, the bedded rocks are intruded by diorite that may be transitional to the andesitic and basaltic volcanic rocks. The bedded and intrusive rocks were regionally metamorphosed to greenschist grade in Late Cretaceous time (Brew, 1996, p. 27). Their premetamorphic age is uncertain. Berg and others (1988, p. 17) note that the intertonguing flysch and volcanic rocks closely resemble Upper Jurassic to mid-Cretaceous marine strata nearby on Gravina Island.? the deposit consists of sericite or chlorite schist containing quartz blebs and abundant disseminated cubes of pyrite, minor chalcopyrite, and small amounts of gold (Wright and Wright, 1908, p. 157). The chalcopyrite locally is oxidized to malachite and azurite. Maas and others (1995, p. 184 and tables 45 and 46) suggest that the Mary T. prospect may be part of a belt of exhalative volcanogenic gold deposits (KC035) that extends along the northeast shore of Smugglers Cove and also includes the U.S. (KC037) and Blue Bucket (KC039) deposits. The average metal contents of their samples of the Mary T. deposit are: 0.95 ppm Au, 2.89 ppm Ag, 2698 ppm Cu, 7.0 ppm Pb, and 117 ppm Zn. Workings dating to the early 1900s include a flooded, 9-foot-deep shaft, a trench, and two pits. The owners at that time reported assays of up to 15% Cu and $11 in gold/ton (Au at $20.67/oz.).

Economic information about the deposit and operations

Development status Prospect
Commodity type Metallic

Mining district

District name Ketchikan

Comments on the workings information

  • Workings / Exploration = Workings dating to the early 1900s include a flooded, 9-foot-deep shaft, a trench, and two pits. The owners at that time reported assays of up to 15% Cu and $11 in gold/ton (Au at $20.67/oz.). The average metal contents of U.S. Bureau of Mines (Maas, 1995) samples of the Mary T. deposit are: 0.95 ppm Au, 2.89 ppm Ag, 2698 ppm Cu, 7.0 ppm Pb, and 117 ppm Zn.

Reference information

Bibliographic references

Comments on the references

  • Primary Reference = Wright and Wright, 1908; Maas and others, 1995

General comments

Subject category Comment text
Deposit Model Name = Distal disseminated Ag-Au? (Bliss, 1992; model 19c)

Reporter information

Type Date Name Affiliation Comment
Reporter 30-JUN-1999 H.C. Berg 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.