oxide. This iron-dominant peroxide also possesses low seismic velocities and high electrical conductivity, making it a potential candidate to explain the D" layer's unique geophysical features.

That iron oxide is rust. Pure iron doesn’t oxidize as aggressively. Examine an old iron engine block and you’ll see a thin surface layer of rust but little penetration into the metal.

But when the task at hand is growing oxide layers on silicon chips in preparation for making your own integrated circuits, it turns out that the old Mark 1 eyeball is all you need. Alert readers ...

Iron oxide—which is now dispersed across Mars—can form under different conditions. Scientists previously thought that the iron oxide on Mars’ surface was hematite, which likely formed ...