A metal detector doesn't actually detect "metal." It detects electrical conductivity and magnetic response — which means every metal shows up differently, and a few barely show up at all. Here's the full picture, from the targets that shout to the ones that whisper.
How Detection Actually Works
The search coil generates an alternating magnetic field. Conductive objects in that field develop eddy currents, which produce a secondary field the detector reads. Two properties decide the response:
- Conductivity — how freely electrons move (silver best, stainless steel worst among common metals)
- Ferromagnetism — iron-family metals distort the field directly, making them easy to find (and easy to discriminate out)
Every Common Metal, Ranked by Detectability
| Rank | Metal | Signal strength | Typical Target ID zone |
|---|---|---|---|
| 1 | Silver | Excellent | High (coin range, top of scale) |
| 2 | Copper | Excellent | High (coin range) |
| 3 | Aluminum | Very good | Low–mid (foil/tab range) |
| 4 | Brass/Bronze | Good | Mid (relic range) |
| 5 | Iron/Steel | Strong but distinct | Iron range (usually discriminated) |
| 6 | Gold | Moderate — size matters | Low–mid (overlaps foil/tabs) |
| 7 | Zinc | Moderate | Mid (zinc penny zone) |
| 8 | Lead | Moderate | Mid (bullet/sinker range) |
| 9 | Titanium | Weak | Low |
| 10 | Stainless steel | Weakest | Low, often choppy |
A few notes worth knowing:
- Gold's ranking surprises people. It's a decent conductor, but natural gold comes small — tiny nuggets need high frequencies to detect. Full guide: can metal detectors detect gold, and dedicated machines in our gold detectors collection.
- Iron is easy to find and easy to ignore — its strong magnetic signature is exactly what discrimination circuits filter out.
- Titanium and stainless are the quiet ones; see our deep dives on titanium and stainless steel.
What Metal Detectors Can't Detect
No conductivity, no signal. Standard detectors will not find: gemstones and diamonds, glass, pearls, ceramic, plastic, paper, bone, or stone artifacts. They also can't see metal-free contraband — which is why airports supplement detectors with body scanners and X-ray. (One exception: some ground-scanning instruments detect voids and disturbed soil, but that's a different technology from a hobby metal detector.)
What You Can Realistically Find
Coins (clad and silver), rings and jewelry, relics (buttons, buckles, bullets), gold nuggets in the right geology, meteorites (most are iron-nickel), and property pins. What you find is mostly about where you hunt — start with our guide to finding the best detecting locations near you, and match the machine to the mission in our metal detectors collection.
FAQ
What metals can a metal detector detect?
All of them, to different degrees — silver, copper, and aluminum are the strongest targets; titanium and stainless steel the weakest. Detection strength follows conductivity and magnetic response.
Can metal detectors find gold?
Yes, but small natural gold requires higher-frequency machines than typical coin detectors. Dedicated gold detectors run at 40+ kHz or use pulse induction.
What can't a metal detector detect?
Anything non-conductive: gemstones, glass, ceramic, plastic, pearls, paper, and stone.
Do metal detectors detect all types of coins?
Yes — all circulating coinage is conductive. Silver and copper coins give the strongest, highest readings; small zinc and aluminum coins read lower.
The Bottom Line
Every metal sets off a metal detector eventually — the question is how loudly. If you know where your target sits on the conductivity ladder, you can pick the right machine and the right settings. Not sure? Our team swings these machines weekly — browse metal detectors or call us at (844) 771-0707.
