What is Iron Ore?
What Makes a Suitable Iron Ore?
An iron ore is a rock or mineral from which iron can be economically extracted. These ores are usually rich in iron oxides.
Not all iron-bearing rocks make suitable ores. The iron content, mineral form, and ease of processing are all critical factors.
The most important iron ore minerals are hematite, magnetite, goethite, and limonite. Each plays a significant role in global iron production.
Main Types of Iron Ore
Hematite is the most widely mined iron ore. It has a high iron content and commonly occurs in massive deposits and banded iron formations.
Hematite is typically red to reddish-brown and may appear earthy or metallic.
Magnetite contains a higher percentage of iron than hematite and is naturally magnetic. Although it often requires more processing, it's an important source of iron in many regions.
Goethite is a hydrated iron oxide and one of the most common iron-bearing minerals at the Earth’s surface. It forms through the weathering of iron-rich minerals in the presence of oxygen and water. Many modern iron ore deposits are dominated by goethite, either alone or mixed with hematite.
Limonite is not a single mineral but a general term for mixtures of hydrated iron oxides, mainly goethite. Often called brown iron ore, it forms in heavily weathered environments.
How Iron Ore Forms
Some of the world’s oldest iron ore deposits formed in ancient oceans, where dissolved iron combined with oxygen released by early life forms. This process produced banded iron formations, which are still mined today.
Other iron ore deposits formed through volcanic activity, hydrothermal fluids, or long-term chemical weathering. In warm, wet climates, weathering can concentrate iron by removing other elements, leaving behind iron-rich material dominated by goethite.
Where Iron Ore Is Found
Iron ore occurs on every continent, but the largest producers are Brazil, Australia, China, India, and Russia. Brazil and Australia supply a large proportion of the world’s iron ore.
Many major iron ore mines exploit vast, near-surface deposits, allowing extraction on an enormous industrial scale.
After oil, iron ore is one of the world’s most important commodities. Iron is essential for the production of steel, which underpins modern infrastructure, construction, transport, and manufacturing.
Global demand for steel has increased dramatically in recent years. As a result, many high-grade iron ore deposits are becoming depleted, and lower-grade ores, particularly those rich in goethite, are becoming increasingly important.
Article Photos
The photo at the top of our article is a hematite-rich iron ore: Courtesy of James St. John.
The second photo, oolitic iron, is a sedimentary iron ore rock composed of tiny, rounded iron-rich grains. Photo: Courtesy of Stan Celestian.
Pop-up photos
Hematite, magnetite, goethite, limonite: Courtesy of Stan Celestian.
