North Star Mine (Hellroaring Plateau, Beartooth Mountains, Montana, USA) 1 : 無料・フリー素材/写真
North Star Mine (Hellroaring Plateau, Beartooth Mountains, Montana, USA) 1 / James St. John
| ライセンス | クリエイティブ・コモンズ 表示 2.1 |
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| 説明 | The Red Lodge Mining District is located near the southeastern termination of the Beartooth Mountains, southwest of the town of Red Lodge in southern Montana, USA. Active mining took place during the 1940s. Most of the old, small mines occur on the high plateaus or just below the eroded plateau edges (for example, along the northwestern margin of Rock Creek Canyon). The black rocky slope just left of the snow and the ~dark-colored depression in the slope to the left of that is the site of the old North Star Mine.Mines in the Red Lodge District targeted chromium ores in the form of black-colored chromitite rocks hosted in greenish-colored serpentinite. In this area, lenses, or pods, or fault-chopped stratiform bodies of serpentinite occur among high-grade metamorphic rocks such as quartzites, gneisses, migmatites, amphibolites, etc. Chromitite is a coarsely-crystalline textured, intrusive igneous rock that is rich in the mineral chromite (FeCr2O4 - iron chromium oxide).The rocks in the Beartooth Mountains are very old. They are principally Archean in age (2.5+ billion years old). The chromite-bearing serpentinite bodies of the Red Lodge District were originally chromite-bearing peridotites (dunites) of early Neoarchean age, or older. Granulite-grade to upper amphibolite-grade regional metamorphism at about 2.75 Ga altered the original dunites to serpentinites. The rocks of the area were also altered by greenschist-grade metamorphism between 1.6 to 1.8 billion years ago, during the late Paleoproterozoic.Locality: view from the Beartooth Highway of the North Star Mine (a.k.a. North Star Claim), near the eroded edge of Hellroaring Plateau, northwestern side of Rock Creek Canyon, southeast of Hellroaring Lakes & southwest of the town of Red Lodge, Red Lodge Chromite District (Red Lodge Mining District; Hellroaring Mining District), Beartooth Mountains, southern Montana, USA (45° 02' 19.20" North latitude, 109° 27' 02.20" West longitude) |
| 撮影日 | 2008-08-30 12:11:19 |
| 撮影者 | James St. John |
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