The Cuyuna Range is an inactive iron range to the southwest of the

Mesabi Range The Mesabi Iron Range is a mining district and mountain range in northeastern Minnesota following an elongate trend containing large deposits of iron ore. It is the largest of four major iron ranges in the region collectively known as the Iro ...

, largely within

Crow Wing County, Minnesota Crow Wing County is a County (United States), county in the East Central part of the U.S. state of Minnesota. As of the 2020 United States census, 2020 census, the population was 66,123. Its county seat is Brainerd, Minnesota, Brainerd. The cou ...

. It lies along a line between

Brainerd, Minnesota Brainerd ( ) is a city and the county seat of Crow Wing County, Minnesota, United States. Its population was 14,395 at the 2020 United States census, 2020 census. Brainerd straddles the Mississippi River several miles upstream from its confluen ...

, and Aitkin, Minnesota. The width ranges from 1 to 10 miles (1.6 to 16 km).

Discovery

Though covered by

Pleistocene The Pleistocene ( ; referred to colloquially as the ''ice age, Ice Age'') is the geological epoch (geology), epoch that lasted from to 11,700 years ago, spanning the Earth's most recent period of repeated glaciations. Before a change was fin ...

glacial drift In geology, drift is a name for all sediment (clay, silt, sand, gravel, boulders) transported by a glacier and deposited directly by or from the ice, or by glacial meltwater. Drift is often subdivided into unstratified (unsorted) drift ( glac ...

up to 200 feet thick, 1859 surveyors noted compass deflection while in the area. The range was surveyed by Cuyler Adams, using a dip needle in 1895. With partners, he located ore by drilling in 1903. The word "Cuyuna" is an amalgamation of the first three letters of Cuyler's name with "Una", the name of his dog. The Kennedy mine shaft reached ore in April 1908 and the first shipment was made via rail on 11 April 1911. Open pit mining started at the Rowe mine in 1912. In addition to the iron, the ore was rich in

manganese Manganese is a chemical element; it has Symbol (chemistry), symbol Mn and atomic number 25. It is a hard, brittle, silvery metal, often found in minerals in combination with iron. Manganese was first isolated in the 1770s. It is a transition m ...

, which was useful during

World War I World War I or the First World War (28 July 1914 – 11 November 1918), also known as the Great War, was a World war, global conflict between two coalitions: the Allies of World War I, Allies (or Entente) and the Central Powers. Fighting to ...

, with 32 mines operating. At the height of the mining, the Cuyuna Range was the location of the worst mining disaster in Minnesota, the Milford Mine disaster. On February 5, 1924, a new tunnel was blasted too close to nearby Foley Lake, and water rushed in, killing 41 miners. Mining on the range continued until 1984. Also like the Vermilion Range, mining slowed as it became more economical to extract

taconite Taconite () is a variety of banded iron formation, an iron-bearing (over 15% iron) sedimentary rock, in which the iron minerals are interlayered with quartz, chert, or carbonate. The name ''taconyte'' was coined by Horace Vaughn Winchell (1865– ...

deposits from the

, which were closer to the surface. Additionally, the surface mines were safer than the mines deep underground.

Cuyuna Country State Recreation Area Cuyuna Country State Recreation Area (CCSRA) is a state park unit of Minnesota, USA, being developed to rehabilitate a portion of the Cuyuna Range where mining pits and piles of waste rock were left behind after decades of open-pit mining for i ...

now occupies portions of the range where mining pits and rock deposit stockpiles were left behind by the miners. The Cuyuna Lakes Trail is also located near the former mines.Crosby Brainerd MN , Trail Bicycling, Biking, Hiking, Cycling, Touring
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Geology

The rocks in the district consist of tightly folded layers parallel to the axis of the Lake Superior Syncline. These folds trend to the northeast. The rocks have been slightly

metamorphosed Metamorphic rocks arise from the transformation of existing rock to new types of rock in a process called metamorphism. The original rock (protolith) is subjected to temperatures greater than and, often, elevated pressure of or more, causi ...

. The main iron ore bearing formation is the middle

Precambrian The Precambrian ( ; or pre-Cambrian, sometimes abbreviated pC, or Cryptozoic) is the earliest part of Earth's history, set before the current Phanerozoic Eon. The Precambrian is so named because it preceded the Cambrian, the first period of t ...

Trommald Formation, which belongs in the Animikie Group. This is a

chert Chert () is a hard, fine-grained sedimentary rock composed of microcrystalline or cryptocrystalline quartz, the mineral form of silicon dioxide (SiO2). Chert is characteristically of biological origin, but may also occur inorganically as a prec ...

containing oxidized iron in the form of

hematite Hematite (), also spelled as haematite, is a common iron oxide compound with the formula, Fe2O3 and is widely found in rocks and soils. Hematite crystals belong to the rhombohedral lattice system which is designated the alpha polymorph of . ...

and

goethite Goethite (, ) is a mineral of the diaspore group, consisting of iron(III) oxide-hydroxide, specifically the α- polymorph. It is found in soil and other low-temperature environments such as sediment. Goethite has been well known since ancient t ...

. Some

clastic Clastic rocks are composed of fragments, or clasts, of pre-existing minerals and rock. A clast is a fragment of geological detritus,Essentials of Geology, 3rd Ed, Stephen Marshak, p. G-3 chunks, and smaller grains of rock broken off other rocks by ...

quartz Quartz is a hard, crystalline mineral composed of silica (silicon dioxide). The Atom, atoms are linked in a continuous framework of SiO4 silicon–oxygen Tetrahedral molecular geometry, tetrahedra, with each oxygen being shared between two tet ...

sand Sand is a granular material composed of finely divided mineral particles. Sand has various compositions but is usually defined by its grain size. Sand grains are smaller than gravel and coarser than silt. Sand can also refer to a textural ...

s and

argillaceous Clay minerals are hydrous aluminium phyllosilicates (e.g. kaolin, Al2 Si2 O5( OH)4), sometimes with variable amounts of iron, magnesium, alkali metals, alkaline earths, and other cations found on or near some planetary surfaces. Clay mineral ...

layers. The

agate Agate ( ) is a banded variety of chalcedony. Agate stones are characterized by alternating bands of different colored chalcedony and sometimes include macroscopic quartz. They are common in nature and can be found globally in a large number of d ...

variant Binghamite is found only in the Cuyuna Range.

Communities

* Cuyuna, Minnesota *

Crosby, Minnesota Crosby is a city in Crow Wing County, Minnesota, Crow Wing County, Minnesota, United States. The population was 2,386 at the 2010 United States Census, 2010 census. It is part of the Brainerd, Minnesota, Brainerd Brainerd micropolitan area, Micr ...

* Ironton, Minnesota * Trommald, Minnesota * Riverton, Minnesota * Manganese, Minnesota

References

External links

Cuyuna Lakes Trail

{{Authority control Geography of Crow Wing County, Minnesota Geology of Minnesota Iron ore deposits

Discovery

Geology

Communities

See also

References

Further reading

External links