The Mesabi Range
The largest and most productive Range began shipments in 1892 from the Mountain Iron Mine. From the 1890's to the present over 4 billion tons were removed from more than 350 mines along its 110 mile length. (2) More than 75% of the production of iron ore in the United States has come from the Mesabi Range. Mesabi is the Ojibwa word for "Giant".
The Merritt Brothers are credited with the first economic discovery of Mesabi iron near Virginia, Minnesota. It wasn't until the Duluth, Missabe, and Northern Railroad (DM&N) linked the Mesabi Range to docks in Duluth Harbor that mining could begin in earnest. The first year’s rail shipments were 4,245 tons of ore. The early railroads to the Mesabi and Vermillion Ranges eventually merged to form the Duluth, Missabe, and Iron Range Railroad (DM&IR) in 1937.
Early mining was underground directed by Cornish mining "captains", but it was quickly discovered that it was far cheaper and easier to mine this ore by open pit methods. By the 1920's most of the underground operations had been closed or modified to open pits.
As the "natural ores" or "red ores" of hematite were approaching exhaustion in the 1950's, mining switched to the un-oxidized and primary taconite ore whichis lower grade (approximately 25% to 30% iron) and requires much more sophisticated concentrating and agglomerating before being shipped as taconite pellets containing approximately 65% iron. The taconite process was developed by Professor E. W. Davis of the University of Minnesota Mines Experiment Station. The first taconite processing plant was in production in the mid-1950s in Babbitt, Minnesota. Following the passage of the Taconite Amendment in 1964 which changed the method of taxation for taconite producers, there was a boom in mine and plant development on the Mesabi. Two additional rail connections were built from the mines to Silver Bay and Taconite Harbor on the north shore of Lake Superior. Several taconite mines and processing facilities are currently operating on the Mesabi Range.
It has long been the goal of Mesabi miners to produce a pure iron product in northern Minnesota. In 2010 a new plant began production of 97% iron nuggets. The nuggets, along with iron and steel scrap, are used in electric arc steelmaking furnaces.
The Minnesota Division of Lands and Minerals has developed an innovative system that combines historic maps of underground mines with current surface topography to display the mines in 3-D. (3) Because many of the underground mines were eventually consumed by open pits the system enables the viewer to see the original extent of underground mining.
A new chapter in the history of the Mesabi Range is currently unfolding. Copper and nickel bearing ores have been discovered beneath the iron formations in the eastern Mesabi. Several mining companies are actively evaluating these deposits and environmental permitting is underway for initial development. Because these ores contain sulfide minerals, prospective mine operators will have to ensure the regulators that there will not be acid rock drainage that could pollute the pristine lakes in northern Minnesota.
The Vermillion Range
The Vermillion Range extends from Tower to Ely, Minnesota. While the Mesabi Range had large tonnages of iron ore close enough to the surface to enable open pit mining, the Vermillion Range formation was primarily deep underground. This very competent rock allowed underground mining. Eleven underground mines were located along the Vermillion Range. In 1883 Charlemagne Tower built the Duluth and Iron Range Railroad (D&IR), linking the town of Tower with Two Harbors on the shore of Lake Superior. Starting in 1884, lake freighters delivered the ore to the steel mills through the lower lakes ports. In 1888, the railroad was extended to the mines in Ely, Minnesota.
The Soudan Mine was nearly 1/2 mile underground and now hosts the Tower Soudan State Park along with the University of Minnesota's High Energy Physics Lab. Both can be visited by public tours that descend on the original skip hoist of the mine.
Production on the Vermillion Range reached over 103 million tons from 1867 to 1967 when the Pioneer Mine in Ely was closed. (2) Average dry iron grades ranged from 55% to over 62%. (4) The origin of this Range is volcanic and consists of inter-bedded chert, magnetite, and hematite.
It's said that the hematite ores of the Soudan mine were so pure that they could be welded together. Underground mining at the Soudan was clean and relatively safe and that gave the mine the nickname of "The Cadillac of Underground Mines". When the Soudan closed in 1962 it was sold by United States Steel to the State of Minnesota for $1 under the condition it would become a State Park. (5)
The Cuyuna Range
"The Cuyuna iron range in east-central Minnesota is unique in the Lake Superior region because of its large manganiferous iron-ore resources. It consists of three areas--the Emily District, the North range, and the South range. Although much smaller than the Mesabi iron range to the north, the Cuyuna was a major producer of iron ore for 80 years. More than 106 million tons of ore were mined and shipped from the Cuyuna range between its discovery, in 1904, and 1984, when mining ceased. Although the iron ore contained more than 10 percent manganese, the manganese was never economically feasible to recover because it was too difficult to separate from the iron. New technology, which involves in situ leaching of the manganese while leaving behind the iron, has been investigated as a possible mining method." (6) Average grades for the shipped ores ranged from 30% to 55% natural dry iron. (4) The origin of these Cuyuna ores was essentially the same as those of the Mesabi Range.
The recent drilling and investigation of cores has also provided new data that geologists at the Minnesota Geological Survey are using as a basis for reinterpreting the formation of the Cuyuna North range. This reinterpretation sets the Cuyuna range apart from the traditional Lake Superior-type iron formations.
The Gunflint Range
The Gunflint Range is located in northern Minnesota and continues into Northwestern Ontario, Canada. It is a continuation of the Mesabi Range to the southwest. The two have been separated by the intrusion of the Duluth Gabbro intrusive complex. J. G. Norwood discovered the Gunflint Range in 1850 after mention of iron ores by Frenchmen 70 years earlier.
The deposit is on the west end of Gunflint Lake in Cook County, MN, and extends into Ontario for a total length of 32 km. From 1888 to 1893 the Paulson Mine, the principle shaft on the Gunflint, was being prepared for production, but didn't come to realization. (7) No ore was ever shipped from the Gunflint. The cherts (i.e. flint) of the Gunflint formation are noted for their Precambrian microfossils.
CLICK ON IMAGES TO ENLARGE
Map of the Minnesota Iron Ranges.
Early Power Shovel In a Mesabi Iron Range Open Pit.
View of the Hull Rust Mahoning Mine on the Mesabi Iron Range.
Duluth Ore Docks ca1904. Taconite pellets from the Mesabi Range continue to be shipped from these docks and those in Silver Bay and Two Harbors, MN and Superior, WI
Headframe and Hoist House at the Soudan Mine on the Vermillion Iron Range.
Underground Mining Scene on the Vermillion Iron Range.
Open Pit Mining on the Cuyuna Iron Range.
View of the Abandoned Paulson Shaft on the Gunflint Iron Range.