A metal detector detects every metal, because every metal conducts electricity, and most hobby detectors will also tell you roughly which kind of metal it is. The strongest, cleanest signals come from silver, copper, brass and aluminum. Iron and steel are easy to detect but read in their own zone, which is why a detector can be set to ignore them. The weak ones are stainless steel, titanium and small pieces of gold. What a metal detector cannot detect at all is anything that is not metal: gemstones, glass, ceramic, plastic, pearls, bone and stone.
How a detector tells one metal from another
The search coil puts out an alternating magnetic field. Any conductive object inside that field develops small circulating currents, and those currents make a field of their own that the coil picks up. Two properties of the object decide what the detector hears and what number it shows:
- Conductivity. How freely the metal carries current. Silver and copper carry it best, so they give the loudest, highest-reading signals. Stainless steel and titanium carry it poorly, so they give weak, low-reading signals.
- Magnetism. Iron, steel and some nickel alloys are ferrous: they distort the coil's field directly as well as conducting. That makes them easy to detect and easy to separate from everything else, which is what the discrimination control on a detector is doing when you turn iron off.
Size, shape and depth matter as much as the metal itself. A silver dollar and a silver earring back are the same metal, but one is a booming signal at a foot down and the other is a whisper at three inches. A metal detector does not detect only magnetic metals, and it does not detect only "precious" metals. It detects conductivity, and then reports where the target sits on a scale from ferrous iron at one end to high-conductivity silver at the other.
Every common metal, from loudest to quietest
The order below is how these metals behave under a hobby detector in the sizes you actually find them, not a pure conductivity chart. The target ID column is approximate; every detector scales it differently, and ground, depth and target size move the number around.
| Metal | Signal | Ferrous? | Where it usually reads |
|---|---|---|---|
| Silver | Strongest | No | Top of the scale, above copper coins |
| Copper | Very strong | No | High, the copper penny zone |
| Aluminum | Strong | No | Low to mid, foil and pull tab zone |
| Brass and bronze | Strong | No | Mid, where buttons, buckles and shell casings sit |
| Iron and steel | Strong, but in its own zone | Yes | Bottom of the scale, usually discriminated out |
| Zinc | Moderate | No | Mid, the zinc penny zone |
| Lead | Moderate | No | Mid, bullets and sinkers |
| Gold | Moderate, and size decides it | No | Low to mid, overlapping foil and pull tabs |
| Titanium | Weak | No | Low |
| Stainless steel | Weakest | Usually not | Low and often broken up |
Two things in that table trip up new detectorists. Aluminum is a strong signal even though it is cheap, which is why a park hunt is mostly pull tabs and foil. And gold, which everyone expects at the top, sits in the same band as that aluminum trash. The posts linked in the table go into each metal in detail.
Can a metal detector find gold?
Yes. Gold is a good conductor, better than brass or zinc. The reason it ranks lower in practice is size and alloy. Natural gold is mostly small: a nugget the size of a match head is a good day in most US ground. A small target makes a small signal no matter what it is made of, and a general-purpose coin detector running at a low frequency may not respond to it at all. Jewelry is alloyed, and 10k or 14k gold reads lower than pure gold would. Dedicated gold detectors solve this by running higher frequencies, typically 18 kHz and up, with 40 kHz and higher for the smallest gold, or by using pulse induction for depth in mineralized ground. Our guide to detecting gold is linked from the table above, and the gold detectors collection has the machines built for it.
What a metal detector cannot detect
If it does not conduct electricity, the coil cannot see it. That rules out gemstones and diamonds, glass, pearls, ceramic, plastic, paper, wood, bone and stone artifacts. A loose diamond is invisible; a diamond in a gold ring is found because of the ring. Arrowheads and pottery are invisible unless they happen to sit next to a nail. The exception people ask about, caches and buried containers, works only when the container or its contents are metal: a glass jar of silver coins is a strong target, the same jar full of paper money is not.
Walk-through security detectors at airports and courthouses are the same physics with a different job. They are tuned to respond to a certain mass of metal, so a belt buckle, keys or a phone sets them off while a single earring usually does not. The things they cannot see are the same things a hobby detector cannot see, which is why airports add body scanners and X-ray.
What you can realistically find
Coins, both modern clad and older silver. Rings and other jewelry, most often lost at beaches, swimming spots and parks. Relics: buttons, buckles, musket balls, cartridge cases, tools and hardware from old home sites. Gold nuggets, if you are in gold-bearing ground with a detector built for it. Meteorites, at least the iron-nickel ones, which are the kind a detector finds and which read as a strong ferrous or mixed signal. Property pins and sprinkler heads, which is a real use for a cheap detector. What you find depends far more on where you swing than on what the detector can sense; our post on finding places to metal detect near you is the right next read.
What to do next
If you want coins and jewelry, any current metal detector with a target ID display will sense every metal in the table and let you ignore the iron. If you want small gold, you need a gold-specific machine, and the gold detectors collection is where to start. If you only need to find a property pin or a lost tool, the cheapest detector we sell will do it.
