The word "kobalt" appears in the writings of B. Valentine and Paracelsus as a description of an elf imagined by the Teutins and the Ancient Scandinavian. These "elfs" used to haunt the mines, destroying the work of the miners. The word derived from the German "kobald", which means evil spirit. In some mining regions there were specific prayers to protect the miners from those "kobalds" and other evil spirits. This term was also used to the so-called "false ores", i.e, the ores incapable of giving any useful metal when submitted to extraction processes. Gradually this term was confined to the minerals used in the production of blue glass and smalts. In 1735, Brandt pointed out that the primary cause to the blue color of those glass and smalts was due to the presence of a metal or semi-metal, that he called "cobalt rex". Brandt was the first to isolate this metal in 1742.