What is the machine you use to find buried coins and gold called?

Buried coins and gold are most commonly located with a metal detector. This device emits an electromagnetic field that can penetrate beneath the ground to detect buried metals.

Since most coins are made of some form of metal, a metal detector is well suited to the task of finding them. The downside to a metal detector is that it will also be triggered by metallic deposits in soil, so it is best to do some research on the terrain that is being searched before visiting. Some metal detectors also can generate false positives over saltwater, although this is not true of all of them.