​MIERES, a town of northern Spain, in the province of Oviedo, 12 m. by rail S.E. of Oviedo, on the river Caudal, a tributary of the Nalon. Pop. (1900), 18,083. Mieres is the chief town of a mountainous, fertile and well-wooded region in which coal, iron, and copper are extensively mined and sulphur and cinnabar are obtained in smaller quantities. The town contains large iron foundries and chemical works, and has an active trade in fruit, cider, timber and live stock.