SKH-1c-2012-07 Spiked Head

Description

Seventh in the sequence of spiked heads cataloged for 2012, SKH-1c-2012-07 documents yet another instance of rim-to-portrait die cracking on a Lincoln Shield Cent struck at Philadelphia. What makes the spiked head phenomenon particularly instructive for understanding die mechanics is its predictability — the junction between a high-relief design element and the die rim acts as a natural stress concentrator, analogous to a notch in an engineering component. Each time the die strikes a planchet, compressive and tensile forces cycle through the steel, and the portrait-rim boundary accumulates fatigue damage faster than surrounding areas. When a micro-crack nucleates and begins to propagate, it creates the characteristic recessed line in the die that coins then reproduce as a raised spike. The 2012 Philadelphia cent carried Brenner's obverse portrait — by then over a century old in concept — paired with the still-new Shield reverse by Lyndall Bass. At least eight spiked heads have been cataloged for this date, as the companion entry SKH-1c-2012-08 confirms, indicating that 2012 dies experienced typical fracture rates. Cuds on Coins maintains the catalog for these varieties.

External References