Steel

Steel is iron with exactly the right amount of carbon—too little and it's soft wrought iron, too much and it's brittle cast iron. For three millennia, steelmaking was alchemy: smiths knew that certain processes produced superior metal, but nobody understood why. The carbonization happened by accident, in the reducing atmosphere of charcoal forges.

Indian smiths produced wootz steel (Damascus steel) by 300 BCE through a crucible process that remains imperfectly understood. Japan developed tamahagane through repeated folding that distributed carbon evenly. But these were artisanal products—a single sword could take months. Mass production remained impossible.

The breakthrough came in 1856 when Henry Bessemer discovered that blowing air through molten pig iron burned off excess carbon, leaving steel. The process took 20 minutes instead of days. Within a decade, steel rails replaced iron rails (lasting 10x longer), steel beams enabled skyscrapers, and steel ships displaced wooden hulls. Annual production leaped from thousands to millions of tons.

Why Britain? Charcoal scarcity had forced British ironmakers to develop coke-fired blast furnaces, which produced the high volumes of pig iron that made Bessemer's process economical. The adjacent possible aligned: chemistry explaining carbon's role, railroads creating demand, and coal deposits providing fuel.

By 2026, steel remains the skeleton of civilization—2 billion tons produced annually—but faces pressure from aluminum, carbon fiber, and recycling requirements. China produces half the world's steel, a path-dependent result of its 1990s industrialization.