Bioleaching is getting metals from their ores by using living organisms. This is much cleaner than the traditional method using cyanide. Bioleaching is one of several methods used to recover copper, zinc, lead, arsenic, antimony, nickel, molybdenum, gold, silver, and cobalt.
Bioleaching uses certain types of bacteria to produce a solution called a "leachate". By leaving these bacteria with a low-grade metal ore, they can produce leachates which have a compound of that metal. Because this is in a solution it can be used in electrolysis to make the pure metal. This only produces small amounts each time, and is repeated to make it economically viable.