Iron is by mass the most common element on Earth, forming much of Earth's outer and inner core.
Core Principles & Analysis
Iron smelting spread from around 1200 BCE to launch the Iron Age, though earlier artifacts like Tutankhamun's dagger were forged from meteoritic iron.
It is the most abundant element on Earth by mass thanks to the planet's core, is ferromagnetic at room temperature, and carries oxygen in blood as the heart of hemoglobin.
Nearly all mined iron becomes steel for construction, vehicles, and machinery, and iron catalysts drive the Haber-Bosch ammonia process.