Porous Planchet

I'll take a stab.  post 1, image 1 looks genuine to me; very regular. Post 2, image 2, is a "maybe", because there is a fair amount of variation in the width of the "lands". Post 3, I don't think either coin is genuine, the first one is just very irregular, and the second is just plain weird, like an Oreo with the filling licked out and the 2 halves stuck together. then plated. 

On 9/8/2020 at 7:02 PM, Insider said:

Almost anytime you learn something "new" it is a good thing.

 

Answer:  When the oxidation on a coin becomes terminal BLACK, the surface under it is etched.  When the black color is removed chemically, the underlying surface is granular and grayish.  This was a difficult quiz because the marks resemble many things we see on coins.  This SLQ is very "special" because of the way the corrosion occurred (streaks resembling a lamination, planchet flaw, or strike thru).  Most terminal toning appears on a coin's rim - often associated with beautiful rainbow color going inward.  The images below is terminal toning away from the rim.  When it is removed, a corroded surface will be present.  This surface can be seen on the Bust Half.

 

 

what had me stumped was the very linear nature of the corroded areas, what could have caused that? The first photo above shows blotchy black matter on the coin, the second shows another linear patch where presumably gunk was removed. What could do that, contact with a rubber band for years?  PVC?