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Magnetite crystals with a cubic habit are rare but have been found at Balmat, St. Lawrence County, New York, [47] [48] and at Långban, Sweden. [49] This habit may be a result of crystallization in the presence of cations such as zinc. [50] Magnetite can also be found in fossils due to biomineralization and are referred to as magnetofossils. [51]
The process by which lodestone is created has long been an open question in geology. Only a small amount of the magnetite on the Earth is found magnetized as lodestone. Ordinary magnetite is attracted to a magnetic field as iron and steel are, but does not tend to become magnetized itself; it has too low a magnetic coercivity.
As of 2019, magnetite iron ore is mined in Minnesota and Michigan in the United States, eastern Canada, and northern Sweden. [8] Magnetite-bearing banded iron formation is mined extensively in Brazil as of 2019, which exports significant quantities to Asia , and there is a nascent and large magnetite iron ore industry in Australia .
Horizons containing magnetite as the dominant mineral have been extensively mined since 1955 to produce iron ore pellets; the term 'taconite' has consequently been colloquially adapted to describe the magnetite iron-formation ores (taconite iron ore), the mining, milling, magnetic separation, and agglomerating process (taconite process), and ...
Many companies have mined the area over the last century, including the Diamond Jo Quarry. [4] The complex has developed a unique soil series, Magnet, which has several inches of dark reddish brown loam over reddish brown clay or clay loam. The Magnet is present only over 5000 acres at the complex and a small outlier at Potash Sulphur Springs. [5]
Ironsand is found worldwide. Although the iron mineral composition of the ironsand is mostly magnetite, the sand is usually mixed with other types of sand that wash downriver or ashore from mountainous or underwater deposits. [3] The exact composition of the sand mixture may vary drastically even in the same geographic region.
Banded iron formation from the Barberton Greenstone Belt, South Africa. A typical banded iron formation consists of repeated, thin layers (a few millimeters to a few centimeters in thickness) of silver to black iron oxides, either magnetite (Fe 3 O 4) or hematite (Fe 2 O 3), alternating with bands of iron-poor chert, often red in color, of similar thickness.
44% of mining facilities in the United States are located in forests. Large-scale mining in areas of Latin America, like Brazil, release pollutants detrimental to neighboring rainforests. [38] Copper mining efforts in the Carajas Mineral Province in Brazil result in 6,100 km of deforestation every year. [38]