Beneath the ancient iron-rich landscapes of Western Australia, a quiet geological process may be quietly rewriting humanity's understanding of where energy can come from. Scientists have found that magnetite, an iron oxide mineral embedded in some of Earth's oldest rock formations, produces hydrogen when met with hot pressurized water — not through human engineering, but through the patient chemistry of the deep earth. A new study has sharpened this picture considerably, revealing that the physical form of the rock — how broken, how porous, how exposed — determines how much hydrogen it can yie