Northern Rocky Mountains

Part of a continental margin arc that formed along the western margin of North America
Tract ID 003pCu9004
Country United States of America
Commodity Cu
Study area name United States revised
Tectonic setting continental margin
Deposit type porphyry copper
Grade-tonnage model General porphyry copper model (Singer and others, 2008)
Geologic age
Geologic feature age Late Cretaceous through Oligocene
Generalized age Tertiary-Paleogene
Oldest rocks age 99.6Ma
Youngest rocks age 23.03Ma
Age range 76.57Ma
Identified Cu resources 40,000,000metric tons
Mean Cu (t/sq km) 208t/sq km
Map scales used 500K

Results of the assessment

Assessment date 2010
Estimators Steve Ludington, Jane Hammarstrom, Gilpin Robinson, and 1996 Team
Assessment depth 1km
Quantitative assessment Yes

Estimated number of deposits

Number of deposits Confidence level
1 90%
6 50%
14 10%
14 5%
14 1%
Mean estimated deposits 6.83 ±4.63 (0.68%)
Probability of mean 0.33
Probability of no copper 0.04

Estimated deposit density

Known
deposits
Total
deposits
Area
(sq km)
Deposit density
per 100,000 sq km
8 14.83 124,990 12

Mean estimated tonnage

Copper 26,000,000
Molybdenum 720,000
Gold 670
Silver 8,600
Ore 5,300

Undiscovered copper resource

Confidence level 90% 50% 10% 5%
Tonnage 630,000 15,000,000 64,000,000 96,000,000

Economic analysis

Fraser country Idaho*-Montana-Wyoming
Fraser type 0.9%
Fraser high 0.1%
Typical cost 1%
High cost 0%
Infrastructure setting Typical
Comments on depth default
Expected depth distribution
0 - 250m 0.25
250m - 500m 0.25
500m - 1km 0.5
Economically recoverable resources
Copper 17,000,000t
Molybdenum 350,000t
Gold 350t
Silver 5,300t
Probability no econ recoverable 0.11
Econ NPV 4,900x $1M
Exp dollars 36.35x $1M/100,000 sq km
Exp value class Medium

Bibliographic references

General U.S. Geological Survey National Mineral Resource Assessment Team (2002)
Economic Robinson and Menzie (2012)

Deposits and prospects associated with this tract

Name Type State Country Development Details
Caribou Mountain prospect Idaho United States Occurrence Details
Chessman prospect Montana United States Occurrence Details
Continental/Butte deposit Montana United States Producer Details
Cumo prospect Idaho United States Occurrence Details
Eagle Creek prospect Wyoming United States Occurrence Details
Emigrant prospect Montana United States Occurrence Details
Golconda prospect Montana United States Occurrence Details
Gold Hill prospect Montana United States Occurrence Details
Goose Lake prospect Montana United States Occurrence Details
Heddleston deposit Montana United States Occurrence Details
Independence prospect Montana United States Occurrence Details
Kirwin deposit Wyoming United States Occurrence Details
New World prospect Montana United States Occurrence Details
Robinson Creek prospect Wyoming United States Occurrence Details
Rochester prospect Montana United States Occurrence Details
Silver Creek deposit Wyoming United States Occurrence Details
Stinkingwater deposit Wyoming United States Occurrence Details
Sunlight prospect Wyoming United States Occurrence Details
Beavertown prospect Montana United States Occurrence Details
Bobcat Gulch deposit Idaho United States Occurrence Details
Clouds Home Peak prospect Wyoming United States Occurrence Details
Morning Glory prospect Montana United States Occurrence Details
Radersburg prospect Montana United States Occurrence Details
Yellow Ridge prospect Wyoming United States Occurrence Details