Bacteria modify the global mineral cycle in two important ways: they induce nearby minerals to precipitate (settle out of solution), and they internally manufacture minerals. Bacteria swimming in a river help precipitate the great gold deposits of South Africa. Today, these wee wonders head for the mines in Russia. Miners pump microbes and water into thin or hard-to-reach veins.
Initial research indicates that microbes biologically induce over 27 kinds of minerals. Which minerals these versatile fellows form depends upon their environment and their own genetic capabilities.