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

Mesabi Range The Mesabi Iron Range is a mining district 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 Iron Range of Minnesota ...

, largely within

Crow Wing County, Minnesota Crow Wing County is a county in the East Central part of the U.S. state of Minnesota. As of the 2020 census, the population was 66,123. Its county seat is Brainerd. The county was formed in 1857, and was organized in 1870. Crow Wing County i ...

. It lies along a line between

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

, and

Aitkin, Minnesota Aitkin ( ) is a city in Aitkin County, Minnesota, United States. The population was 2,168 at the 2020 census. It is the county seat of Aitkin County. History Before the establishment of City of Aitkin, a transient community of Lexington was lo ...

. The width ranges from 1 to 10 miles (1.6 to 16 km).

Discovery

Though covered by

Pleistocene The Pleistocene ( , often referred to as the ''Ice age'') is the geological epoch that lasted from about 2,580,000 to 11,700 years ago, spanning the Earth's most recent period of repeated glaciations. Before a change was finally confirmed in ...

glacial drift 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 with the symbol Mn and atomic number 25. It is a hard, brittle, silvery metal, often found in minerals in combination with iron. Manganese is a transition metal with a multifaceted array of industrial alloy use ...

, which was useful during

World War I World War I (28 July 1914 11 November 1918), often abbreviated as WWI, was one of the deadliest global conflicts in history. Belligerents included much of Europe, the Russian Empire, the United States, and the Ottoman Empire, with fightin ...

, 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 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 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

Binghamite (Cuyuna North Range, Minnesota, USA)

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 Formation may refer to: Linguistics * Back-formation, the process of creating a new lexeme by removing or affixes * Word formation, the creation of a new word by adding affixes Mathematics and science * Cave formation or speleothem, a secondar ...

is the middle Precambrian Trommald Formation, which belongs in the

Animikie Group The Animikie Group is a geologic group composed of sedimentary and metasedimentary rock, having been originally deposited between 2,500 and 1,800 million years ago during the Paleoproterozoic era, within the Animikie Basin. This group of formati ...

. 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 ...

containing oxidized iron in the form of hematite 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

quartz Quartz is a hard, crystalline mineral composed of silica ( silicon dioxide). The atoms are linked in a continuous framework of SiO4 silicon-oxygen tetrahedra, with each oxygen being shared between two tetrahedra, giving an overall chemical ...

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

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 minerals ...

layers. The

agate Agate () is a common rock formation, consisting of chalcedony and quartz as its primary components, with a wide variety of colors. Agates are primarily formed within volcanic and metamorphic rocks. The ornamental use of agate was common in Anci ...

variant Binghamite is found only in the Cuyuna Range.

Communities

Cuyuna, Minnesota Cuyuna ( ) is a city in Crow Wing County, Minnesota, United States. The population was 332 at the 2010 census. It is part of the Brainerd Micropolitan Statistical Area. The city lies within its namesake, the Cuyuna Range, a line of iron-bea ...

Crosby, Minnesota Crosby is a city in Crow Wing County, Minnesota, United States. The population was 2,386 at the 2010 census. It is part of the Brainerd Micropolitan Statistical Area. Crosby is adjacent to its twin city of Ironton, in the Cuyuna iron range ...

* Ironton, Minnesota * Trommald, Minnesota *

Riverton, Minnesota Riverton is a city in Crow Wing County, Minnesota, United States. The population was 117 at the 2010 census. It is part of the Brainerd Micropolitan Statistical Area. Riverton is located between Brainerd and Ironton, where the Mississippi Riv ...

* 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