Iron ore is the foundational substrate of the industrial world, primarily extracted as oxides of iron. The two most economically significant minerals are:
These minerals are predominantly found in Banded Iron Formations (BIFs)—ancient sedimentary rocks that record the oxygenation of the Earth's early atmosphere. To the naturalist, BIFs are not merely deposits, but the fossilized remains of a planetary crisis. Approximately 2.4 billion years ago, the emergence of cyanobacteria—the first architects of photosynthesis—began pumping free oxygen into the oceans. This oxygen reacted with dissolved ferrous iron, causing it to precipitate as iron oxides that settled in rhythmic, alternating layers of chert and hematite. The very steel of our skyscrapers is, in essence, the rusted breath of prehistoric microbes.
The supply chain is characterized by extreme geographic concentration and massive volumetric throughput.
The "62% Fe benchmark" has historically governed pricing, though the industry is transitioning toward a 61% Fe standard as average ore grades decline.
To convert iron oxide into metallic iron, the oxygen must be chemically stripped. This is achieved in a blast furnace using coke (processed coal) as both a fuel and a reducing agent.
The chemical reduction occurs in stages:
Fluxing: Limestone ($\text{CaCO}_3$) is added to the charge. It calcines into lime ($\text{CaO}$), which reacts with silica ($\text{SiO}_2$) impurities to form a liquid slag ($\text{CaSiO}_3$), which is then tapped off, leaving molten pig iron.
The iron ore supply chain is a study in the "tyranny of bulk." Because the value-to-weight ratio is low, the economics are entirely dependent on the efficiency of the rail-to-ship interface. Any disruption in the Pilbara or Carajás corridors creates immediate volatility in the global steel market.