SKH-1c-1972-03 Spiked Head

Description

Documented on July 16, 2016, by the Cuds on Coins attribution team, SKH-1c-1972-03 is the third spiked head variety cataloged for the 1972 Philadelphia Lincoln Memorial cent. No cross-references to other attribution systems (including the James Corbin catalog that documented the first two entries) have been established for this variety. The absence of a Corbin cross-reference may indicate this die was not represented in Corbin's independent research, or that the cross-referencing between catalogs was not completed for later-attributed varieties. The July 2016 attribution date — roughly four months after the first two entries were documented in March — suggests a separate submission from a different collector or a later review of material that had been awaiting processing. SKH-1c-1972-03 represents a third distinct obverse die from the 1972 Philadelphia production run that developed the characteristic portrait-apex cracking responsible for the spiked head phenomenon. Die fatigue cracking at Lincoln's head is driven by the extreme depth of the die cavity at this point — the deepest recess in the entire obverse die — which experiences the highest compressive stress during each strike cycle and is therefore most susceptible to fatigue crack initiation over thousands of repeated impacts. The crack propagates along grain boundaries in the die steel until it reaches the die face, at which point metal begins flowing into the crevice during subsequent strikes, building up the distinctive raised spike visible on examination of the finished coin.

Attribution History

• Discovered by Earl M
• Cross reference: none. 07/16/2016.
• Expert attribution by Cuds on Coins

External References