1993 D Kennedy Thick planchet

Stew

Something different I have not seen yet while my son was doing a science experiment with some balanace scales he had made he wanted to weigh some coins, pulled out some Kennedy halves and noticed one that looked thicker than the rest got out the calipers and it is a full millimeter wider than the rest . Anybody have any Ideas, thoughts or just a guess. I am not a metallurgist and am not sure if varied pressure or what would cause it. Looks like a full strike on both sides. Will post picture soon as I get fresh batteries for the camera

GrumpyEd

Go by weight not how thick it looks.

Thickness might be from the rim being higher.
On modern cents the ones from mint sets are often thicker because they have higher rims but weigh the same as normal. I'm sure similar things happen on other denoninations.

If it weighs substantialy more you might have something.

Stew

Thank you for the input I'll pick-up some digital scales and check it out

…

this phenomenon also occurs on proof coins. Im not sure what causes it, besides perhaps specially produced planchets, but thicker planchets on Kennedy halves are quite common.

FredWeinberg

It could be what's called a "finned rim".

This is when the obv. die is slightly mis-aligned, and
allows for the metal to flow up between the 'crevice'
between the collar and the die.

It could be a small amount of the rim that is 'raised',
and makes the coin appear to be thicker from the edge
viewing, or stacking.

In most cases, it involves 20-40% of the edge.

A scan at an angle, or of the edge itself, would be good
to see......

Fred