The Vermilion Range exists between

Tower, Minnesota Tower is a city located in St. Louis County, Minnesota, Saint Louis County, Minnesota, United States. As of the 2020 United States census, 2020 census, the city had a total population of 430. State Highways 1 (Minnesota State Highway 1, MN 1), 1 ...

and

Ely, Minnesota Ely ( ) is a city in St. Louis County, Minnesota, St. Louis County, Minnesota, United States. The population was 3,268 at the 2020 United States census, 2020 census. Located on the Vermilion Range (Minnesota), Vermilion iron range, Ely once ha ...

, and contains significant deposits of

iron ore Iron ores are rocks and minerals from which metallic iron can be economically extracted. The ores are usually rich in iron oxides and vary in color from dark grey, bright yellow, or deep purple to rusty red. The iron is usually found in the f ...

. Together with the Mesabi, Gunflint, and Cuyuna ranges, these four constitute the Iron Ranges of northern

Minnesota Minnesota ( ) is a U.S. state, state in the Upper Midwestern region of the United States. It is bordered by the Canadian provinces of Manitoba and Ontario to the north and east and by the U.S. states of Wisconsin to the east, Iowa to the so ...

. While the Mesabi Range had iron ore close enough to the surface to enable pit mining, mines had to be dug deep underground to reach the ore of the Vermilion and Cuyuna ranges. The

Soudan mine 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, dee ...

was nearly 1/2 mile underground and required blasting of Precambrian sedimentary bedrock.Jackson, Judy
"Notes from Underground"
''Ferminews'', July 19, 2002. The

banded iron formation Banded iron formations (BIFs; also called banded ironstone formations) are distinctive units of sedimentary rock consisting of alternating layers of iron oxides and iron-poor chert. They can be up to several hundred meters in thickness and e ...

in the range consists of a "interbedded sequence" of

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 ...

magnetite Magnetite is a mineral and one of the main iron ores, with the chemical formula . It is one of the iron oxide, oxides of iron, and is ferrimagnetism, ferrimagnetic; it is attracted to a magnet and can be magnetization, magnetized to become a ...

and hematite. Eleven mines operated in the range, with five in the Ely area. The Ely

Trough Trough may refer to: In science * Trough (geology), a long depression less steep than a trench * Trough (meteorology), an elongated region of low atmospheric pressure * Trough (physics), the lowest point on a wave * Trough level (medicine), the l ...

, a synclinal fold, produced 70 million metric tons from the Chandler, Pioneer, Zenith, Sibley and Savoy mines. The largest mine in the range, Soudan, was closed in 1962, and the last mine in the Ely area closed in 1964. Despite the effort needed for the deep mining Soudan mine, the ore obtained was worth the effort; the quality of the

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 . ...

ore was so pure that two pieces could be welded. The bedrock, known as taconite, also contained iron, but in a much lower concentration. After more efficient practices for creating

steel Steel is an alloy of iron and carbon that demonstrates improved mechanical properties compared to the pure form of iron. Due to steel's high Young's modulus, elastic modulus, Yield (engineering), yield strength, Fracture, fracture strength a ...

were discovered, the use of this high-quality ore was abandoned due to its more costly mining expense. The Soudan hematite was used in the open hearth furnace, where the density of the ore, called Vermilion Lump, was needed to break through the floating slag to cause the molten charge to roil and burn off the impurities. When the newer blast furnaces came into use, the expensive Vermilion Lump was no longer needed. New processes were developed to extract the iron from the taconite by using

open-pit mining Open-pit mining, also known as open-cast or open-cut mining and in larger contexts mega-mining, is a surface mining technique that extracts rock (geology), rock or minerals from the earth. Open-pit mines are used when deposits of commercially ...

and producing taconite pellets. This method produced a processed ore product at a significantly reduced cost. Once proven successful, the technical change resulted in Minnesota's iron industry centering on the Mesabi Range, where the taconite was much easier to access.

References

*United States Patent 2,806,775 Charging Ore and the Like and its Preparation

External links

{{Coord, 47, 51, N, 92, 4, W, display=title Geology of Minnesota Iron ore deposits

See also

References

Further reading

External links