Treating a subterranean formation includes injecting a magnetically permeable material into the formation and energizing the magnetically permeable material using electromagnetic radiation. The magnetically permeable material reacts to the electromagnetic radiation by producing heat. In some embodiments, a fracturing fluid is made magnetically permeable, injected into the formation to fracture the formation, and heated in response to electromagnetic radiation applied to the magnetically permeable material. In some embodiments, electromagnetically heated material is caused to explode. In some embodiments, the magnetically permeable material is tracked or monitored for fluid or fracture propagation. A system includes a fluid treatment tool disposed on a tubing string for injecting magnetically permeable material and an electromagnetic wave generator disposed on the tubing string proximate the fluid treatment apparatus for applying electromagnetic radiation to the magnetically permeable material.