My first project during my PhD explored the question of whether the solar system might contain a third type of volcanism. Silicate volcanism is a ubiquitous process on rocky bodies, and cryovolcanism (where the "lava" is generally water) is known to occur in the outer solar system. Our work suggests that in addition to these two, metallic bodies (which are found in the asteroid belt) may also host volcanism. You can read our paper here or at DOI:10.1029/2019GL082542. The background of this page is an artist's conception of what a (very active) ferrovolcanic asteroid might look like, illustrated by Elena Hartley