View source for Physics:Lake Vermilion-Soudan Underground Mine State Park

{{Infobox NRHP
| name                 = Soudan Iron Mine
| nrhp_type            = nhl
| image                = SoudanMine_arf.JPG
| caption              = The 27th level of the Soudan Mine
| location             = Tower-Soudan State Park, Breitung Township, St. Louis County, Minnesota
| nearest_city         = Tower, Minnesota
| coordinates          = {{coord|47|49|24|N|92|14|14|W|display=inline,title}}
| locmapin             = Minnesota#USA
| area                 = {{convert|301|acre|order=flip}}
| built                = 1900
| architect            =
| designated_nrhp_type = November 13, 1966<ref name="nhlsum">{{cite web|url=http://tps.cr.nps.gov/nhl/detail.cfm?ResourceId=685&ResourceType=Site|title=Soudan Iron Mine|access-date=2009-09-08|work=National Historic Landmark summary listing|publisher=National Park Service|url-status=dead|archive-url=https://web.archive.org/web/20120612093902/http://tps.cr.nps.gov/nhl/detail.cfm?ResourceId=685&ResourceType=Site|archive-date=2012-06-12}}</ref>
| added                = November 13, 1966<ref name = nris/>
| refnum               = 66000905<ref name="nris">{{NRISref|version=2010a}}</ref><ref name="nrhpinv">{{Cite journal|title=National Register of Historic Places Inventory-Nomination: Soudan Underground Mine State Park|url={{NHLS url|id=66000905}} |format=pdf|author=Stephen Lissandrello |date=January 3, 1976 |publisher=National Park Service}} and {{NHLS url|id=66000905|title=Accompanying 8 images from 1975.|photos=y}}&nbsp;{{small|(897&nbsp;KB)}}</ref>
| website              = [http://www.dnr.state.mn.us/state_parks/lake_vermilion_soudan/index.html Lake Vermilion-Soudan Underground Mine State Park]
}}

The '''Lake Vermilion-Soudan Underground Mine State Park''' is a Minnesota state park at the site of the '''Soudan Underground Mine''', on the south shore of Lake Vermilion, in the Vermilion Range (Minnesota).  The mine is known as Minnesota's oldest, deepest, and richest iron mine. It formerly hosted the '''Soudan Underground Laboratory'''.  As the '''Soudan Iron Mine''', it has been designated a U.S. National Historic Landmark.

==History==
[[File:Iron Ranges.jpg|thumb|300px|left|Lake Superior Iron Ranges]]
[[Image:Soudan Mine Headframe.jpg|thumb|left|The headframe for shaft #8, still in active use today]]
In the late 19th century, prospectors searching for gold in northern Minnesota discovered extremely rich veins of [[Chemistry:Hematite|hematite]] at this site, often containing more than 65% iron. An open pit mine began operation in 1882, and moved to underground mining by 1900 for safety reasons. From 1901 until the end of active mining in 1962, the Soudan Mine was owned by the United States Steel Corporation's Oliver Iron Mining division. By 1912 the mine was at a depth of 1,250 feet (381 m).<ref>Van Barneveld, Charles E. (1913) ''Iron Mining in Minnesota'', 199. University of Minnesota.</ref> When the mine closed, level 27 was being developed at 2,341 feet (713.5 m) below the surface and the entire underground workings consisted of more than fifty miles of [[Engineering:Drift mining|drifts]], adits, and raises. In 1965, US Steel donated the Soudan Mine to the State of Minnesota to use for educational purposes.<ref name=Ojakangas>{{Cite book |author1=Richard W. Ojakangas |author2=Charles L. Matsch |title=Minnesota's Geology |url=https://archive.org/details/minnesotasgeolog00ojak |url-access=limited |publisher=University of Minnesota Press |year=1982 |isbn=0816609535 |pages=[https://archive.org/details/minnesotasgeolog00ojak/page/n145 127]–130}}</ref>

The primary underground mining method used was known as cut and fill. This involved mining the ceiling and using Ely Greenstone and other waste rock to artificially raise the floor at the same rate as the ceiling was being mined out. As a result, the floor and ceiling were always 10–20 feet (3–6 m) apart. There was no need to move waste rock to the surface, because it was moved short distances and left in place. This technique was particularly suited to the Soudan Mine due to the strength of the hematite formations and the weakness of the encasing Greenstone. This method was not possible in the nearby mines in Ely, Minnesota, because the iron formations there were fractured and thus were not as structurally stable as those at Soudan.{{citation needed|date=December 2021}}

==State park==
The park is in Breitung Township, on the shore of Lake Vermilion in northern Minnesota's Vermilion Range. It has become a popular tourist site, often visited on the way to and from Ely and the Boundary Waters Canoe Area Wilderness.{{citation needed|date=December 2021}}<!-- But true.  I visited on a day trip during a tourist vacation in Ely. 2021-12-26 Acwilson9. -->

The state park is operated under the Department of Natural Resources. It is a National Historic Landmark, meaning that it is also listed on the National Register of Historic Places.<ref name="nhlsum"/>  As of 2021, the surface buildings are open to the public, and during the summer months there are daily tours of the mine.<ref>{{cite web| publisher=Minnesota Departemnt of Natural Resources| date=2021| title=Soudan Underground Mine Tours| url=https://www.dnr.state.mn.us/state_parks/lake_vermilion_soudan/tours.html| accessdate=2021-12-26}}</ref> Visitors are lowered in the antique 1924 electric mine hoist to level 27, the mine's lowest level at 2,341 feet (713.5 m) below ground.<ref>{{cite book| publisher=Minnesota Departemnt of Natural Resources| author=Pointer, James| date=2009| title=Engine House Audio Tour Chapter 12, Stop 11}}</ref><!-- Google search finds this file, but the pseudo-URLs that Google used don't work within Wikipedia: url=http://files.dnr.state.mn.us › state_parks › soudan ; chrome-extension://efaidnbmnnnibpcajpcglclefindmkaj/viewer.html?pdfurl=http%3A%2F%2Ffiles.dnr.state.mn.us%2Fdestinations%2Fstate_parks%2Faudio_tours%2Fsoudan%2Fch12.pdf&clen=54925&chunk=true . 2021-12-26 Acwilson9. --> As of 2021, tours of the previously active underground physics laboratory were no longer offered.<ref name=UMn-SoudanULab_VirtualTour>{{cite web| title=Virtual Tour| date=2012| publisher=University of Minnesota Soudan Underground Laboratory| url=https://www.soudan.umn.edu/background/index_2.shtml| accessdate=2021-12-26}}</ref>

Lake Vermilion State Park, originally separate from Soudan Underground Mine State Park, began with the purchase of about 3,000 acres from [[Company:U.S. Steel|U.S. Steel]] in 2010.<ref name=ParkInfo>[http://www.dnr.state.mn.us/state_parks/lake_vermilion/narrative.html Park Info] {{webarchive|url=https://web.archive.org/web/20140116130116/http://www.dnr.state.mn.us/state_parks/lake_vermilion/narrative.html |date=2014-01-16 }}, Minnesota Department of Natural Resources.</ref><ref>[https://web.archive.org/web/20131101171916/http://files.dnr.state.mn.us/destinations/state_parks/lake_vermilion/final_cooperative_master_plan.pdf Cooperative Master Plan: Lake Vermilion State Park, Soudan Underground Mine State Park, 2011–2020], Minnesota Department of Natural Resources Division of Parks and Trails (December 2010).  Master plan for development of parks.</ref><ref>[https://web.archive.org/web/20140116130145/http://files.dnr.state.mn.us/destinations/state_parks/lake_vermilion/day_use_areas.pdf Lake Vermilion and Soudan Underground Mine State Parks], Minnesota Department of Natural Resources map of two parks indicated separately</ref> The park includes the Stuntz Bay Boathouse Historic District.<ref>{{cite news |last1=Ross |first1=Jenna |title=These 143 historic boathouses offer a peek into Minnesota's past |url=https://www.startribune.com/these-143-historic-boathouses-offer-a-peek-into-minnesota-s-past/572450492/ |work=Star Tribune |date=September 18, 2020| accessdate=2021-12-26}}</ref>  In 2014, the two adjacent parks were combined into one.<ref>{{cite news| url=https://www.minnpost.com/mnopedia/2016/06/once-minnesota-s-deepest-mine-soudan-complex-now-state-park/| title=Once Minnesota's deepest mine, Soudan complex is now a state park| date=June 1, 2016| author=Laine, Mary| publisher=MinnPost| accessdate=2021-12-26}}</ref>

== Underground laboratory ==
[[Image:MINOS Project in Soudan Mine.jpg|thumb|right|MINOS Detector]]
[[File:Jaspilite banded iron formation, Soudan Underground State Park.jpg|thumb|Surface outcrop, folded Soudan Iron-Formation, age about 2.69 billion years. Scratches are from glaciation.]] 
In the 1980s, scientists from the [[Organization:University of Minnesota|University of Minnesota]] began to develop the Soudan Mine as a site for sensitive physics experiments because of the very low rate of cosmic rays in the deep underground site, and also because they could inexpensively use the still-operating mine hoist. The mine laboratory was originally home to the [[Physics:Soudan 1|Soudan 1]] [[Physics:Proton decay|proton decay]] experiment and its successor, [[Physics:Soudan 2|Soudan 2]] which operated from 1989-2001.<ref>{{cite web|title=High Energy Physics Lab|url=http://www.dnr.state.mn.us/state_parks/soudan_underground_mine/physicslab.html|publisher=Minnesota Department of Natural Resources|access-date=2011-04-19|url-status=dead|archive-url=https://web.archive.org/web/20110629173510/http://www.dnr.state.mn.us/state_parks/soudan_underground_mine/physicslab.html|archive-date=2011-06-29}}</ref>  The University and the Minnesota Department of Natural Resources later expanded the laboratory to accommodate other physics projects, such as the [[Physics:MINOS|MINOS]] [[Physics:Neutrino|neutrino]] detector, [[Astronomy:Dark matter|dark matter]] search experiments [[Physics:Cryogenic Dark Matter Search|CDMS]]-II, SuperCDMS, and  [[Physics:CoGeNT|CoGeNT]], as well as work on [[Engineering:Electroforming|electroforming]] copper to create pure radiation-free copper. Low-background materials screening facilities were in use and in continuing development.<ref name=UMn-SoudanULab_History>{{cite web| title=Lab History: Why Underground?| date=2012| publisher=University of Minnesota Soudan Underground Laboratory| url=https://www.soudan.umn.edu/background/index_2.shtml| accessdate=2021-12-26}}</ref><ref name=Fermilab_SoudanFire2011/> The mine was proposed as one possible site for a U.S. Deep Underground Science and Engineering Laboratory, but that project was instead awarded to the Homestake Mine (South Dakota).{{citation needed|date=December 2021}} Parts of the laboratory had been open for daily tours, and there was an annual open house with more access to the facilities and representatives of the experiments to help with the tours and answer questions.<ref name=StPaulPioneerPress_SoudanTours2012>{{cite news|url=http://www.twincities.com/ci_20685072/closed-by-fire-soudan-underground-mine-state-park|title=Closed by fire, Soudan Underground Mine State Park resuming tours| date=May 22, 2012| publisher=St. Paul Pioneer Press| accessdate=2021-12-26}}</ref> The laboratory, along with public tours, were closed circa 2016.<ref name=UMn-SoudanULab_VirtualTour/><ref name=UMn-SoudanULab_History/><ref name=DuluthNewsTribune_SoudanLabClosure2017>{{cite news|url=https://www.duluthnewstribune.com/news/4412347-work-continues-find-tenants-soudan-underground-lab| title=Work continues to find tenants for Soudan underground lab |date=March 3, 2018| author=Kazcke, Lisa L.| publisher=Duluth News Tribune| accessdate=2021-12-26}}</ref>

== 2011 fire ==
A fire broke out late on March 17, 2011, in the main shaft at the 25th level.<ref name=Fermilab_SoudanFire2011>{{cite news|title=Scientists reenter Soudan Underground Laboratory|work=Fermilab Today|url=http://www.fnal.gov/pub/today/archive/archive_2011/soudan_mine_fire.html| access-date=9 August 2015}}</ref>  The fire was smothered using 70,000 gallons of fire-fighting foam, filling the 27th and lowest level of the shaft (27th level) from floor to ceiling. The Underground Laboratory lost power but remained safe. The mine tours were closed for the summer of 2011, but the above ground tours and interpretive center reopened. After a major cleanup effort, underground tours resumed on May 26, 2012.<ref name=StPaulPioneerPress_SoudanTours2012/>

==See also==
*List of National Historic Landmarks in Minnesota
*National Register of Historic Places listings in St. Louis County, Minnesota
*List of Minnesota state parks

==References==
{{Reflist}}

==External links==
*{{cite web |title=Soudan Mine Geology (Geologic Map of the 27th Level West Drift) |url=http://www.d.umn.edu/prc/fieldcamp/2010%20Field%20Camp/PRC-MAP-2010-01.pdf |publisher=University of Minnesota |access-date=January 1, 2023 |archive-url=https://web.archive.org/web/20160428213819/http://www.d.umn.edu/prc/fieldcamp/2010%20Field%20Camp/PRC-MAP-2010-01.pdf |archive-date=April 28, 2016 |date=August 12, 2010}}
*Soudan Iron formation geology, photo galleries:  [https://www.flickr.com/photos/jsjgeology/sets/72157652553006284/], [https://www.flickr.com/photos/jsjgeology/sets/72157652565921094/], [https://www.flickr.com/photos/jsjgeology/sets/72157654754996240/]
*[http://www.dnr.state.mn.us/state_parks/lake_vermilion_soudan/index.html Lake Vermilion-Soudan Underground Mine State Park]
*[http://nrhp.mnhs.org/property_overview.cfm?propertyID=1 National Register of Historic Places: Mines: Soudan Mine]
*[http://www.soudan.umn.edu/ Soudan Underground Laboratory]
*[https://web.archive.org/web/20070703092209/http://www.int.washington.edu/DUSEL/ Deep Underground Science and Engineering Laboratory] (proposed)
*[http://www.towersoudan.com/ Tower Soudan Historical Society]
*[https://web.archive.org/web/20120612093902/http://tps.cr.nps.gov/nhl/detail.cfm?ResourceId=685&ResourceType=Site NHL summary]
*[http://www.timberjay.com/stories/Cleanup-underway-at-Soudan-Mine,8124 Cleanup underway at Soudan Mine Fire]
*[http://www.fnal.gov/pub/today/archive_2011/soudan_mine_fire.html Scientists reenter Soudan Underground Laboratory]
*{{HAER |survey=MN-30 |id=mn0139 |title=Soudan Iron Mine, Tower–Soudan State Park, Tower, St. Louis County, MN |photos=39 |data=1 |cap=2}}



[[Category:Laboratories in the United States]]
[[Category:Underground laboratories]]

{{Sourceattribution|Lake Vermilion-Soudan Underground Mine State Park}}