The ancient mercury mines of Almadén, Spain, open deep new shafts and the 'Castillo' vaulting system following a devastating fire, securing their position as the world's premier supplier of liquid mercury. This expansion is vital for extracting silver in the Americas, linking the Spanish domestic economy directly to colonial production. The labor force relies heavily on 'forzados' (convicted criminals) and enslaved Africans, who endure terrible mercury poisoning, tremors, and respiratory failure. Almadén remains a highly fortified, high-stakes industrial zone critical to global monetary flow.

The horrors of the Almadén mercury shafts deeply influence Spanish Enlightenment literature and political poetry. Writers like Gaspar Melchor de Jovellanos write about the state of Spanish industry and the miserable plight of miners, using Almadén as a symbol of the urgent need for humanitarian and technological reform. The trembling, poisoned bodies of the miners become a bleak metaphor in late 18th-century Spanish verse for an empire decaying from within due to its reliance on toxic, unfree labor.