Thursday, February 13, 2014

Pictures of the Moment - Soudan Underground Mine State Park

Soudan Underground Mine State Park is the only place I know where you can tour an historic iron ore mine and a state-of-the-art physics lab at the same time. I was here in June of 2006. It's a great day for a geologist like me, or anyone who likes mining history.

Shaft #8 headframe. It takes a few minutes to get all the way down the cramped "cage" elevator.

Silhouettes of fellow miners on the tour, illuminated by headlamps 2341 feet below the surface. A 3/4 mile underground rail takes you to the Montana orebody, the deepest workings in the Soudan. Surface mining commenced in 1882, making it Minnesota's oldest operating district, and operations were fully underground in the 20th century.

The underground workings are preserved as they were left in 1962. Later United States Steel (Oliver Mining) donated the property to the state for educational purposes. Soudan was Minnesota's deepest and highest-grade iron ore mine, with hematite ores grading >65% Fe by weight. Ores mined in Minnesota today have less than half the recoverable iron. It was all I could do not to collect a sample.

The picture is a little fuzzy, but I took it.

You pass through a nondescript door from the darkened mine and into a brilliantly-lit physics lab, a segue that has all the hallmarks of a James Bond novel. Here is the MINOS (or Main Injector Neutrino Oscillation Search) neutrino detector. More than 2000 feet underground, the lab also conducts dark matter experiments, the Cryogenic Dark Matter Search (CDMS II).

More than 2600 million years old, banded iron formation of the Soudan Iron-Formation--on Minnesota's Vermilion Range--hosts ores exploited in one of Minnesota's original mining districts. More than 15 million tons of ore were mined here, a small amount compared to much younger near-surface deposits of the nearby Mesabi Range. This stuff makes great clock faces and counter tops when cut and polished. It also looks very nice just where it is, especially after a rain.