Some bacteria break down minerals, while others make them
Geologists are studying bacteria nowadays. It's not that the rock hounds have gone soft. Instead, they've found that geological processes once attributed solely to simple inorganic chemistry have microbial fingerprints all over them. In rocky venues ranging from abandoned mines in California to water wells in Bangladesh to hydrothermal vents on the seafloor, bacteria are at work. If the microbes aren't driving the underlying chemical reactions in those places, they're at least taking advantage of the energy that's being released by these reactions.