The interdisciplinary field of geomicrobiology and microbial geochemistry (GMG) has provided surprising insights into microbial function and preservation in diverse environments. The emerging frontiers in GMG are driven by recent discoveries in material sciences, economic geology, human health, and paleontology. The length-scales and mechanisms by which organisms can transfer electrons are being redefined, which have implications ranging from the formation of ore deposits to microbial function in the human body. Pathways of biomineralization are a critical control for many fossilization processes. Microbiologically produced materials also exhibit great potential for technological and medical applications.