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

Unnamed (southwest Bostwick Inlet)

Occurrence in Alaska, United States with commodities Zinc, Silver
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. Mineral occurrence model information
  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 10307667
Record type Site
Current site name Unnamed (southwest Bostwick Inlet)

Geographic coordinates

Geographic coordinates: -131.71777, 55.19874 (WGS84)
Relative position This unnamed occurrence is on the southwest shore of Bostwick Inlet, near its mouth, about 0.9 mile north of the south-projecting point at the north entrance of Seal Cove. The site is in section 16, T. 77 S., R. 91 E., of the Copper River Meridian. It corresponds to loc. 309 in Maas and others (1995). The location is accurate within 0.1 mile.

Site location context

Political divisions (FIPS codes)

Ketchikan Gateway(Borough)

Alaska(state)

United States(country)

North America(continent)

Land(continent)

USGS map quadrangles

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

Ketchikan SW(quadrangle 1:100,000 scale)

Ketchikan(quadrangle 1:250,000 scale)

Hydrologic units (watersheds)

Ketchikan(hydrologic unit)

Southern Southeast Alaska(hydrologic accounting unit)

Southeast Alaska(hydrologic subregion)

Alaska(hydrologic region)

Federal lands

Tongass National Forest(National Forest)

National Forest UND(Type of land area)

UND(Federal land areas administered by UND)

Geographic areas

Country State
United States Alaska

Commodities

Commodity Importance
Zinc Critical Primary
Silver Secondary

Materials information

Materials Type of material
Pyrite Ore
Sphalerite Ore

Mineral occurrence model information

Model code 184
USGS model code 28a
Deposit model name Massive sulfide, kuroko
Mark3 model number 93

Nearby scientific data

(1) CPxwg
ListMap

Economic information

Comments on the geologic information

  • Geologic Description = Southern Gravina Island is underlain by an assemblage of undivided Silurian or Ordovician metamorphosed bedded and intrusive rocks; a stock and associated dikes of Silurian trondhjemite that cuts the metamorphic assemblage; and a sequence of Upper Triassic carbonate, clastic, rhyolitic, and basaltic strata that unconformably overlies the older rocks (Berg, 1973, 1982; Berg and others, 1988). The rocks are complexly folded and are cut by high-angle faults and by low-angle thrust faults. In many places, the Triassic rhyolite and the rocks beneath it are permeated by microscopic particles of hydrothermal hematite, giving them a pink, purple, or red hue (Berg, 1973, p. 14). This occurrence consists of stratiform layers, up to 1.6 feet thick, of massive pyrite and sphalerite in Upper Triassic rhyolite at its depositional contact with overlying Upper Triassic carbonaceous slate (H.C. Berg, unpublished field data, 1968; Maas and others, 1995, p. 227). The contact strikes west and dips steeply to the north, and is truncated by a NW-striking, high-angle fault along the southwest shore of Bostwick Inlet (Berg, 1973). Samples collected by Maas and others (1995, p. 229) across about 10 feet of mineralized rock contained up to 1.6% Zn and small amounts of Ag. The characteristics and setting of this occurrence indicate that it is a stratiform, volcanogenic massive-sulfide deposit of Late Triassic age. As such, it is the southernmost known occurrence of a belt of Upper Triassic, stratabound, volcanogenic massive-sulfide deposits in southeastern Alaska (Berg, 1981).
  • Age = Late Triassic.

Economic information about the deposit and operations

Development status Occurrence

Comments on exploration

  • Status = Inactive

Mining district

District name Ketchikan

Reference information

Bibliographic references

Comments on the references

  • Primary Reference = Maas and others, 1995

General comments

Subject category Comment text
Deposit Model Name = Kuroko massive sulfide (Cox and Singer, 1986; model 28a)

Reporter information

Type Date Name Affiliation Comment
Reporter 05-JUL-99 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.