Banded iron formations are known as taconite within North America.

Banded iron formations may contain iron in carbonates ( siderite or ankerite) or silicates ( minnesotaite, greenalite, or grunerite), but in those mined as iron ores, oxides ( magnetite or hematite) are the principal iron mineral. Banded iron formations occur exclusively in Precambrian rocks, and are commonly weakly to intensely metamorphosed. quarter (diameter: 24 mm ) shown for scale.īanded iron formations (BIFs) are sedimentary rocks containing more than 15% iron composed predominantly of thinly bedded iron minerals and silica (as quartz). Processed taconite pellets with reddish surface oxidation as used in the steelmaking industry, with a U.S. These are magnetite, titanomagnetite, massive hematite and pisolitic ironstone deposits. There are four main types of iron ore deposits worked currently, depending on the mineralogy and geology of the ore deposits. Iron ore mining methods vary by the type of ore being mined. Increasing iron ore demand, coupled with the depletion of high-grade hematite ores in the United States, led after World War II to development of lower-grade iron ore sources, principally the utilization of magnetite and taconite. These deposits are commonly referred to as 'direct shipping ores' or 'natural ores'. Historically, much of the iron ore utilized by industrialized societies has been mined from predominantly hematite deposits with grades of around 70% Fe. Prehistoric societies used laterite as a source of iron ore. Prior to the industrial revolution, most iron was obtained from widely available goethite or bog ore, for example during the American Revolution and the Napoleonic Wars. The thermodynamic barriers to separating pure iron from these minerals are formidable and energy-intensive therefore, all sources of iron used by human industry exploit comparatively rarer iron oxide minerals, primarily hematite. Although iron is the fourth-most abundant element in the Earth's crust, composing about 5%, the vast majority is bound in silicate or more rarely carbonate minerals (for more information, see iron cycle). The origin of iron can be ultimately traced to formation through nuclear fusion in stars and most of the iron is thought to have originated in dying stars that are large enough to collapse or explode as supernovae. Some iron meteorites are thought to have originated from accreted bodies 1,000 km in diameter or larger. Metallic iron is virtually unknown on the surface of the Earth except as iron-nickel alloys from meteorites and very rare forms of deep mantle xenoliths. JSTOR ( July 2021) ( Learn how and when to remove this template message).Unsourced material may be challenged and removed. Please help improve this article by adding citations to reliable sources. This section needs additional citations for verification. In 2011 the Financial Times quoted Christopher LaFemina, mining analyst at Barclays Capital, saying that iron ore is 'more integral to the global economy than any other commodity, except perhaps oil'.

Iron ore is the raw material used to make pig iron, which is one of the main raw materials to make steel-98% of the mined iron ore is used to make steel. Ores containing very high quantities of hematite or magnetite (greater than about 60% iron) are known as 'natural ore' or 'direct shipping ore', meaning they can be fed directly into iron-making blast furnaces. The iron is usually found in the form of magnetite ( Feģ, 69.9% Fe), goethite ( FeO(OH), 62.9% Fe), limonite ( FeO(OH) The ores are usually rich in iron oxides and vary in color from dark grey, bright yellow, or deep purple to rusty red. Iron ores are rocks and minerals from which metallic iron can be economically extracted. Iron ore being unloaded at docks in Toledo, Ohio.

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