Medina developed the patio process, an intricate amalgamation process utilizing mercury, while mining in Pachuca, Mex., in 1557. The process proved especially useful in America, where fuel and waterpower were scarce. It was introduced into Hungary in 1786 and thence to other parts of Europe. The patio process was effective even with low-grade ores and was used widely up to the 20th century.
From 1576 to 1580 Medina taught theology at the University of Salamanca, where he was a zealous exponent of Thomism and where he formulated the casuistical theory of probabilism, a means of settling moral questions.