ALMADEN, or ALMADEN DEL AZOQUE (in Arabic, the "Mine of Quicksilver"), a town of Spain, in the province of Ciudad Real, lies in the Sierra Morena, 55 miles S.W. of the town of Ciudad Real. It is the Sisapon of the Romans, and is famous for its quicksilver mines, which have been wrought extensively both in ancient and in modern times. They were the richest and most productive in the world until the discovery of quicksilver at New Almaden in California. The annual yield is about 1,400,000 lb, and 4000 workpeople are employed. The principal vein is 25 feet thick ; a depth of 1000 feet has been reached, and the ore increases in richness with the depth of the descent. These mines belong to the Spanish Government, and yield a large revenue. At various periods they have been leased to private speculators. The town has a good hospital and mining schools. Population, 9000.