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<p>[QUOTE=&quot;Conder101, post: 380612, member: 66&quot;]I would say it is crystallization from the annealing of the planchets.&nbsp; Actually the woodgrain and the crystal patterns seen here have similar causes.&nbsp; The woodgrain is caused by the slow cooling of the ingots which allows the crystals to form (and form larger),&nbsp; They are then stretched out into streaks in the rolling of the strip.&nbsp; The crystals seen on these coins is from the annealing the planchets receive before striking.&nbsp; </p><p><br /></p><p><br /></p><p>The reason for the difference in the toning is because as the metal cools and the crystals grow the alloy tries to separate so some of the lighter crystals have a higher zinc content than the darker ones do.&nbsp; The two slightly different alloys do not tone at quite the same rate and it causes the different colors. Dipping strips the toning off of both types of crystal and we can no longer see the difference.&nbsp; (When they wee new the woodgrain planchets appeared homogeneous as well.&nbsp; The woodgrain is not that apparent until the lower zinc content tone.&nbsp; The higher zinc areas do not tone as readily and so retain their lighter color.)[/QUOTE]</p><p><br /></p>

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