# Magnetic Detection of Magnetite

I have a tool with a very thin and faded coating of what seems to be magnetite black oxide ($$\mathrm{Fe_3O_4}$$), I’m trying to see if this coating is magnetite, while a chemical test is possible, a magnetic detection test also seems reasonable.

Does anyone know whether a thin layer of magnetite applied to a tool could be detectable through magnetism, or whether there are some specific methods or magnetic detectors I could use for detecting a small amount of magnetite?

— Jack