United States quarters, historically composed of 90% silver and 10% copper, underwent a compositional change in the mid-1960s. This transition involved replacing the silver content with a clad composition consisting of outer layers of copper-nickel bonded to a core of pure copper. This modification resulted in coins with a significantly reduced intrinsic metal value.
The change in composition was primarily driven by a surge in silver prices during the early 1960s. The escalating cost of silver threatened to make the intrinsic metal value of the coins exceed their face value. This created the potential for widespread melting of circulating coinage, destabilizing the monetary system. The shift to clad coinage alleviated this threat and maintained the stability of the circulating currency.