SKH-1c-1993-43 Spiked Head

Description

The mechanical properties of zinc planchets differ markedly from the pre-1982 bronze composition, and these differences directly influence die wear patterns that produce varieties like SKH-1c-1993-43. Cataloged by Cuds on Coins as the forty-third spiked head on the 1993 Philadelphia Lincoln Memorial cent, this variety formed on a die striking planchets whose zinc core registers approximately 2.5 on the Mohs hardness scale — substantially softer than earlier copper alloy cents at roughly 3.0. However, Vickers microhardness testing reveals that the thin copper plating is actually harder than the zinc substrate, creating a composite surface with complex deformation behavior. When the die strikes, the plating resists initial deformation, concentrating contact pressure in a brief pulse before the softer zinc yields and allows metal flow into die cavities. This two-stage impact subjects the portrait area to repeated high-pressure transients that accelerate fatigue crack nucleation — the mechanism that ultimately produces the raised spikes cataloged across the forty-four-variety 1993-P census.

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