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Though many metal detecting aficionados may say they only find pennies and soda-pop can tops during their day-to-day detecting, others have struck it rich. In the last century treasure-hunting enthusiasts toting metal detectors have discovered rare coins, antique medals, and even chests of gold and silver. A man in Texas recently uncovered a rare Civil War battle medal near his home.

The medal sold for $11,000.A California resident found a $5 gold coin that was minted in 1851. At auction the coin was valued at $40,000. A cache of nearly 15,000 late 4th and early 5th century gold and silver coins were discovered by a Brit near Suffolk, England. Those who love metal detecting would tell you that treasure is out there, and half the fun is just looking for it.

Metal detectors use electromagnetic induction to detect metal. Uses include de-mining, the detection of weapons such as knives and guns, especially at airports, geophysical prospecting, archaeology and treasure hunting.

In its simplest form, a metal detector consists of an oscillator producing an alternating current that passes through a coil producing an alternating magnetic field. If a piece of electrically conductive metal is close to the coil, eddy currents will be induced in the metal, and this produces an alternating magnetic field of its own. If another coil is used to measure the magnetic field (acting as a magnetometer), the change in the magnetic field due to the metallic object can be detected.