magnetometer is used to detect
: Magnetometers detect ferrous metals that could be attracted by a magnet. Steel, iron and iron rich rocks. A good way to remember this is that ferrous metals (detectable) rust or stain yellow/orange. Magnetometers will not detect or see nonferrous metals. Gold, silver, lead, copper, aluminum, and some stainless steel. (This makes the underwater mag indispensable for weapon searches). Aluminum cans and pull tabs are not detected.