Ursus

Occurrence in Alaska, United States with commodities Silver, Lead, Arsenic, Copper

Geologic information

Identification information

Deposit ID 10307783
Record type Site
Current site name Ursus

Geographic coordinates

Geographic coordinates: -154.55297, 63.46949 (WGS84)
Relative position The Ursus prospect is located in the southern part of the Mystery Mountains on a prominent north-south ridgeline, at an elevation of 2,000 feet (609 m) in Section 23, T. 23 S., R. 22 E., of the Kateel River Meridian. Location is accurate to within about 3,000 feet (914 m).
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Geographic areas

Country State
United States Alaska

Commodities

Commodity Importance
Silver Primary
Lead Primary
Arsenic Secondary
Copper Secondary

Materials information

Materials Type of material
Galena Ore
Pyrite Ore
Quartz Gangue
Tourmaline Gangue

Alteration

  • (Local) Ankerite in quartz porphyry.

Mineral occurrence model information

Model code 85
USGS model code 22c
Deposit model name Polymetallic veins
Mark3 model number 46

Nearby scientific data

(1) -154.55297, 63.46949

Comments on the geologic information

  • Geologic Description = The Ursus prospect occurs in both tourmaline bearing, pyrite, feldspar porphyry and brown brecciated hornfels. Vein breccias are common in the hornfels. The diffuse mineral zone is marked by strong limonite gossan development and conspicuous ankeritic alteration in the quartz porphyry intrusion. The Ursus prospect is inferred to be Late Cretaceous, based on isotopic ages of plutonic rocks in Mystery Mountains (Patton and others, 1980; Moll and others, 1981) . Ursus is thought to represent an outer mineral zonation away from the central Mystery Mountains and is characterized by anomalous lead, silver and zinc in soils. An inner copper-gold zonation in the central Mystery Mountains is manifested by the Frozen Creek (MD032), Copenhagen (MD030) and Pork Chop (MD0031) copper-gold prospects. Limonitically stained grab samples of quartz-tourmaline veins yielded up to 2.30 percent lead, 1,000 ppm copper, and 4.70 ounces/ton silver (DiMarchi and others, 1997).
  • Age = the Ursus prospect is inferred to be Late Cretaceous, based on isotopic ages of plutonic rocks in Mystery Mountains (Moll and others, 1981).

Economic information

Economic information about the deposit and operations

Development status Occurrence

Comments on exploration

  • Status = Inactive

Mining district

District name McGrath

Comments on the workings information

  • Workings / Exploration = Ursus is one of a number of prospects explored by the mineral industry from 1975 to 1997 as a large porphyry copper-gold system centered on the Mystery Mountains (Andrews, 1978; Bell, 1983; DiMarchi and others, 1997). Limonitically stained grab samples of quartz-tourmaline veins yielded up to 2.30 percent lead, 4.7 ounces/ton (161 grams/tonne ) silver, and 1,000 ppm copper (DiMarchi and others, 1997).

Reference information

Links to other databases

Agency Database name Acronym Record ID Notes
USGS Alaska Resource Data File ARDF MD033

Bibliographic references

  • Deposit

    Andrews, Tom, 1978, Summary of Progress, Doyon Project, Mystery Mountains, (Block 10): Anchorage, Alaska, WGM Inc., 24 pages (Held by Doyon Ltd., as proprietary report 78-42).

  • Deposit

    Patton, W.W., Jr., Moll, E.J., Dutro, J.T., Jr., Silberman, M.L., and Chapman, R.M., 1980, Preliminary geologic map of Medfra quadrangle, Alaska: U.S. Geological Survey Open-File Report 80-811-A, 1 sheet, scale l:250,000.

  • Deposit

    Moll, E.J., Silberman, M.L., and Patton, W.W. Jr., 1981, Chemistry, mineralogy, and K-Ar ages of igneous and metamorphic rocks of the Medfra quadrangle, Alaska: U.S. Geological Survey Open-File Report 80-811C, 15 p., 2 sheets, scale 1:250,000.

  • Deposit

    Bell, J.D., 1983, Mystery Mountains Area, Block 10, Doyon Region, Kuskokwim District: Hecla Mining Company Summary Report, 25 pages.

  • Deposit

    DiMarchi, J.J., and Frantz, P.S., 1997, Annual Report for 1997-Doyon Option Lands, Block 10: ASA Inc.-Montague Gold Joint Venture Report, Volume II: Unpublished report, 189 p. (Report held by Doyon, Limited, Fairbanks, Alaska.)

Comments on the references

  • Primary Reference = DiMarchi and others, 1997

General comments

Subject category Comment text
Deposit Model Name = Polymetallic vein (Cox and Singer, 1986; model no. 22c)
Deposit Other Comments = See Mystery Mountains West (MD029) prospect. The Ursus Prospect is on land selected or owned by Doyon Ltd. For additional information contact Doyon Ltd. at 210 1st Ave., Fairbanks, Alaska, 99701.

Reporter information

Type Date Name Affiliation Comment
Reporter 06-JUN-98 Bundtzen, T.K. Pacific Rim Geological Consulting