The Aznalcóllar mine spill occurred in April 1998 when a dam at the Los Frailes mine in Aznalcóllar, Spain, collapsed. This disaster released approximately 5 million cubic meters of toxic sludge, containing heavy metals like copper, zinc, and lead, into the surrounding environment, affecting the nearby Guadiamar River and surrounding areas. The spill had significant ecological and economic impacts, leading to the contamination of water and soil. Cleanup efforts were initiated, and the incident raised awareness about the importance of mining regulations and environmental protection to prevent similar disasters in the future.