Can you weigh the quarter in grams? If you can't you can ask a jeweler or coin dealer to do it for you. Here are a couple possibilities. Both are bonding mill errors.In the first type of error one clad strip was not properly bonded to the core strip by the bonding mill. This caused the clad to layer separate from the copper core after blanking but before the coin was struck. The weight of a normal clad quarter is 5.67 grams. If the clad strip is missing the quarter will weigh about 4.70 grams. Another possibility is also a bonding mill error where the clad strip was never actually bonded to the core strip to start with. Definition: During the bonding process, two outer coils of thin clad strip (75% Cu / 25% Ni) are bonded to a middle coil of thick core strip composed of pure copper. If the leading end of one of the clad strips lags behind the other two strips during insertion into the bonding mill, the leading end of the composite strip will have only two layers instead of three. Likewise, if one clad strip terminates prematurely at the trailing end of the bonded strip, that trailing end will also only have two layers, one of copper-nickel and one of pure copper. In each case, the bi-laminar section of strip will be rolled to full thickness. Any blank punched out of that section of the strip will also weigh the same as a normal coin (5.67 grams). A normal-weight missing clad error will also result when a large gap is present or opens up within one of the clad strips. This gap will be filled by the copper core during bonding and subsequent rolling. This is a very rare type of rolling mill error.
