Coeur Mine, Evolution Mining District, Shoshone County, Idaho, USAi

Regional Level Types
Coeur Mine	Mine
Evolution Mining District	Mining District
Shoshone County	County
Idaho	State
USA	Country

Southeast of Osburn

Structure: Osburn Fault, 1.5 km north of Coeur shaft, N75W 60-80SW Placer Creek Fault, 3.5 km south of Coeur shaft Big Creek Anticline, north overturned limb strikes N55W, axial plunge 10 to 20 N, axial plane dips 55SW. Polaris Fault, N55W 50-75SW, cuts north limb of Big Creek anticline, a tension fracture extending from the Osburn to the Placer Creek faults. St. Elmo Fault, N50W 60SW, shows reverse movement. Mineral Point Fault Fort Wayne Fault, N60W 60-70SW, shows normal displacement. Silver Standard Fault, N60W 65SW, shows normal movement.

Tectonics: Belt Basin

Deposit: 16 of the patented claims were leased from the coeur d'alene mines corp and 22 of the patented claims were leased from the rainbo W min. And mill. Co. In 1966 ; these 2 companies merged in 1968

Deposit type: Polymetallic veins

Development: 38 PATENTED, 4 UNPATENTED CLAIMS. ABOUT 53299 FT TOTAL DIAMOND DRILLING. CALADAY CROSSCUT TO HALFWAY POINT OVER 2000 FT FROM PORTAL. ; TOTAL$: 20 ; MILL$: 10 ; MILL.CAP: 502 TPD ; ECON.YEAR: 1976 ; ECON.COM: EXPLORATION AND DEVELOPMENT WORK TOTALED $10 MILLION The Siderite vein, the main vein of the Mineral Point mining operation was discovered by Coeur d'Alene Mines Corp in 1935. The Commodore Truxton vein was discovered in 1945 and the Wire Silver vein in 1950 in the course of mine development and exploration. The first orebody in the modern Coeur mine operations was discovered in 1969 by Asarco, Inc.

Geology: St. Regis - Revett transition zone extends near surface to 3700 ft level

Rock formation(s): St. Regis Formation, Revett Formation

Ore(s): Ore-bodies (massive siderite veins) occur in a wedge of Revett Formation quartzite in the footwall of the Polaris Fault. Revett Formation rocks have been uplifted here over 1 kilometer. Veins pinch out rapidly when they pass into argillite. Boundaries of veins at the intersection of fractures and bedding. Clean Revett Formation quartzite is the best host rock, sericitic quartzite in the St. Regis Formation is a relatively poor host rock. Mineralized fractures occupy fractures of five orientations, one parallel to the Osburn and Placer Creek Faults, and two sets of conjugate fractures related to left-lateral and right-lateral movement on the Osburn and Placer Creek Faults.

Other Databases

Link to USGS MRDS:	10107346

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References