A standard United States quarter currently in circulation is not magnetic. If you place a common magnet against a modern quarter, you will find no attraction. The magnetic properties of a coin are determined by its metallic composition, and the metals used in the modern quarter do not interact with a magnetic field. This characteristic is tied to the specific layered structure and the alloys chosen for the currency since the mid-1960s.
The Composition of a Modern US Quarter
The quarter dollar minted since 1965 is known as “clad coinage” because it is constructed like a metallic sandwich. It consists of three distinct layers bonded together. The center layer, or core, is made of pure copper.
This copper core is enveloped on both sides by an outer layer composed of a cupronickel alloy. This alloy is 75% copper and 25% nickel, which provides the coin with its silver-like appearance and durability. Overall, the coin’s composition is approximately 91.67% copper and 8.33% nickel by weight.
The copper core is visible along the reeded edge of the coin as a reddish-orange stripe. This layered structure was chosen to provide a durable coin that could be mass-produced without the metal’s intrinsic value exceeding the face value.
Why the Coin’s Materials Are Not Magnetic
The reason a modern quarter is not attracted to a magnet lies in the fundamental magnetic nature of its metals. Materials that stick to a common magnet are known as ferromagnetic, such as pure iron or pure nickel. Although the outer layer contains nickel, a ferromagnetic element, the coin is not magnetic due to the low concentration of nickel within the alloy.
The cupronickel cladding is only 25% nickel, which is below the threshold required for the material to exhibit ferromagnetism at room temperature. When nickel is alloyed with a high percentage of copper, the copper atoms disrupt the magnetic domains within the nickel atoms. This results in an alloy that is either diamagnetic or very weakly paramagnetic, meaning it is not attracted to a magnet.
The large inner core of pure copper is also diamagnetic. Since both the core and the outer layers lack the necessary atomic structure for ferromagnetism, the entire quarter remains non-magnetic.
Historical Composition Changes
The non-magnetic nature of the quarter also applies to its historical predecessors, despite their different composition. Quarters minted before 1965 were made of an alloy that was 90% silver and 10% copper. This composition changed due to rising silver prices, which made the metal content more valuable than the 25-cent face value.
Neither silver nor copper are ferromagnetic materials, meaning these older coins are also not magnetic. Silver is a diamagnetic metal, similar to copper. Therefore, whether testing a pre-1965 silver quarter or a modern clad quarter, the result is the same: no attraction to a magnet.
A few specialized or foreign coins, such as certain wartime issues made of steel, are ferromagnetic. These exceptions highlight how the specific metallic choice, rather than the coin’s denomination, determines its magnetic properties.