slgwv's photos with the keyword: acid-mine drainage

Red Mountain Creek, off US 550 (the "million-dollar highway") between Ouray and Silverton, Colorado. The rusty stain is just that--iron oxyhydroxides--that's mostly a result of acid mine drainage (AMD). Sulfide minerals oxidize in the presence of water and oxygen, yielding sulfuric acid which in turn puts metals, including iron, into solution. The dissolved iron then oxidizes further from atmospheric oxygen and precipitates. Because it's just rust, it's harmless if not particularly attractive. Other dissolved metals, tho, can be considerably more of an environmental hazard. Over the last few decades there have been efforts to isolate the drainage from old tailings heaps upstream to minimize further AMD. The inset shows a close-up of the staining along the creek.

Along the Durango to Silverton narrow-gage excursion train, Colorado. The river's name is shortened from the Spanish original: El Río de las Animas Perdidas , "The River of Lost Souls." The story is that several members of a Spanish expedition in the 1700s were swept away and drowned while trying to cross the river. Note the rust staining along the river banks. It's from acid-mine drainage, due to sulfide oxidation making sulfuric acid that in turn mobilized metals. Not all of it is a result of mining, but mining certainly exacerbated it! The stain is harmless--it's literally just rust (iron oxides and hydroxides), but it doesn't add to the esthetic experience--

Close-up of impoundment to catch acid-mine drainage.

A classic case of acid-mine drainage. It's a US EPA Superfund site. The ponds are to keep the leachate from flowing into the Carson River.

An abandoned sulfur mine in California, just over the state line from Nevada. It's now a Superfund site due to sulfuric acid formed by the oxidizing sulfur. Not only has the acid itself had a deleterious effect on draining into the local streams, but the acidity also leaches metals into solution up to toxic levels. This is a textbook case of "acid mine drainage" from abandoned mines.