Image: Empire & Tilden Iron Mines, MI

Description: The Operational Land Imager (OLI) on Landsat 8 captured this image of iron mines in northern Michigan on September 11, 2013. Although the mined areas look like one facility from a satellite perspective, there are two separate mines in this scene. The Empire Mine, which produces about 5.5 million tons of magnetite each year, is on the east side of the complex; Tilden Mine, which produces about 8 million tons of hematite and magnetite each year, is just to the west. Exposed rock and dirt in the mines appear gray compared to the surrounding forest. Large pits, piles of rock, processing facilities, roads, and railroad tracks are visible within both mines. The water in the Gribben Tailings Basin and the water reuse pond serving Tilden Mine is orange due to the high concentration of hematite, a mineral that often has a rusty brown color. In contrast, the water in the tailings basin for Empire Mine is blue because that mine only produces magnetite. You can also see Palmer and West Ishpeming, nearby towns where many mine employees live. The two mines are boons for the local economy, generating about $775 million in economic activity every year and supporting 1,600 jobs, according to Cliffs Natural Resources, the company that operates the two mines. However, the mines also have significant environmental impacts. For instance, a report released by Michigan’s Department of Environmental Quality found that sediment in Goose Lake sediment and in some nearby streams have elevated levels of selenium due to mining. Though essential to life, selenium can be toxic to wildlife in high concentrations. In response to the elevated selenium levels, environmental authorities have issued fish consumption advisories for several waterways near the mines.
Title: Empire & Tilden Iron Mines, MI
Credit: http://earthobservatory.nasa.gov/IOTD/view.php?id=84243&src=eoa-iotd
Author: NASA Earth Observatory image, Landsat data
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License: Public domain
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