All a metal detector does is notice changes in it's magnetic field due to the presence of metal. So, no.
So metal detectors only detect magnetic metals, not non-magnetic?
No. Aluminum isn't magnetic in the "sticks to iron" sense, but creates a disturbance in the electro-magnetic field the detector generates, and the disturbance is actually what the detector reacts to.
I honestly don't understand the underlying physics well enough to know why it works, but that's how it works.
Induction, electromagnetic induction to be precise, is the term you are hunting for.
*rubs forehead*
Why are you asking, Dos? I gots to know.
What about porcelain?
I'm familiar with some... specific intelligence sources that say certain modern porcelain can make a firearm invisible to metal detectors.
All you need is a magnetic cloaking device. Problem solved.
So metal detectors only detect magnetic metals, not non-magnetic?
You thought all those guys on the beach with metal detectors were going after what? Car keys? The car?
https://www.explainthatstuff.com/metaldetectors.html