Has anyone figured out what is the cause of the wood grain look seems like the 80's cents only have that look
Resulted from impurities in the alloy or concentrations of pure copper that did not properly blend with the 5% tin and zinc added to it. When these less than perfect ingots were rolled into strip, from which blanks would later be punched, the concentrations were flattened and stretched into the patterns seen on the finished coins. Invisible when first struck, these flaws appeared only after the coin was exposed to atmospheric agents that caused the copper concentrations to tone more quickly than the properly mixed portions of the planchet. 1980 is known for their woodies. Woodies don't have much if any premium but I do keep the nicer ones I find.