Ursus

Occurrence, Inactive

Commodities and mineralogy

Main commodities Ag; Pb
Other commodities As; Cu
Ore minerals galena; pyrite
Gangue minerals quartz; tourmaline

Geographic location

Quadrangle map, 1:250,000-scale MD
Quadrangle map, 1:63,360-scale B-4
Latitude 63.47
Longitude -154.55
Nearby scientific data Find additional scientific data near this location
Location and accuracy 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).

Geologic setting

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).
Geologic map unit (-154.552338122671, 63.4694022902816)
Mineral deposit model Polymetallic vein (Cox and Singer, 1986; model 22c).
Mineral deposit model number 22c
Age of mineralization The Ursus prospect is inferred to be Late Cretaceous, based on isotopic ages of plutonic rocks in Mystery Mountains (Moll and others, 1981).
Alteration of deposit Ankerite in quartz porphyry.

Production and reserves

Workings or 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).
Indication of production None
Reserve estimates None.

Additional 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.

References

MRDS Number 10307783

References

Andrews, Tom, 1978, Summary of Progress, Doyon Project, Mystery Mountains (Block 10): Anchorage, Alaska, WGM Inc., 24 p. (Held by Doyon, Limited, Fairbanks, Alaska, as proprietary report 78-42).
Bell, J.D., 1983, Mystery Mountains Area, Block 10, Doyon Region, Kuskokwim District: Hecla Mining Company Summary Report, 25 p.
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.)
Reporters Bundtzen, T.K. (Pacific Rim Geological Consulting)
Last report date 6/6/1998