What processes concentrate iron compared to aluminium

Iron concentrates through magmatic differentiation, hydrothermal deposition, and banded iron formation processes, while aluminium remains dispersed in silicates and oxides unless intense tropical weathering forms bauxite.

Processes concentrating iron

• Magmatic segregation: Dense iron oxides (magnetite, ilmenite) crystallize and settle out of magma.
• Hydrothermal activity: Hot fluids deposit iron sulfides (pyrite) and oxides in veins.
• Banded iron formations (BIFs): Precambrian seas precipitated alternating iron oxides and silica layers, forming vast iron ore reserves.
• Weathering: Iron oxides like hematite and goethite accumulate in laterites, but aluminium remains dominant in bauxites.

Contrast with aluminium

• Aluminium rarely forms concentrated metallic ores except through lateritic bauxite formation.
• Iron is more easily mobilized in hydrothermal and marine environments.