4.1" Miocene Volcanic Bomb - Nevada

Volcanic bombs are extrusive igneous rocks formed as products of volcanic eruptions. They occur as volcanoes eject viscous fragments of lava into the air. As they fly through the air, they acquire an aerodynamic shape, bearing a variety of different appearances depending on composition (mostly basaltic), speed, and spin. In some cases, these volcanic bombs can be thrown miles away from where they originated.

The shape they obtain hardens before they hit the ground, but during their flight they may collide with other bombs, creating interesting paired volcanic bomb specimens.