Bartolomé de Medina was the chief alchemist of the Cerro Rico mines. As such, his duties were mostly concerned with managing and improving the refining processes by which raw silver and mithril ore was transformed into ingots for transport. In this field he was unimaginative, adding little to the centuries old amalgamation processes.
However, he also took an active interest in applying chemicals to improve worker productivity, pioneering a process that transformed coca leaves into a white powder that was far more powerful then the raw leaves themselves.
After his transformation into a creature of shadow, he continued his research into biologically focused alchemy, creating several new rituals around the creation of flesh and bone golems.