1968-D KHD 50c..3x mintmark

[iloveikes]

I always get shot down on my mint mark so-called issues, but, I keep learning...is this triple-stacked normal as a mintmark change in 1968 or something?
Thanks.
Cal

[wavysteps]

Hi Cal - It does look like it could be machine doubling or in this case machine tripling.

While machine doubling is easily explained, it becomes a different ball game when more than two apparent strikes on a design element are seen as with your coin.

A theory of how this may happen goes like this. The coin, when struck, resonates at a certain frequency, much like a bell when struck. When the coin hits the retreating die (as what happens in machine doubling) multiple hits to the design element are seen because the coin is vibrating at its resonating frequency. So, even though the coin bounces only once into the retreating die three or more of shelf like doublings will be seen on a design element affected.

BJ Neff

[diamond]

You can find up to four sets of "steps" in some cases of machine doubling. Even more difficult to explain are those cases of machine doubling in which the movement is in two, or even three different directions.

[19Lyds]

Hi Cal - It does look like it could be machine doubling or in this case machine tripling.

While machine doubling is easily explained, it becomes a different ball game when more than two apparent strikes on a design element are seen as with your coin.

A theory of how this may happen goes like this. The coin, when struck, resonates at a certain frequency, much like a bell when struck. When the coin hits the retreating die (as what happens in machine doubling) multiple hits to the design element are seen because the coin is vibrating at its resonating frequency. So, even though the coin bounces only once into the retreating die three or more of shelf like doublings will be seen on a design element affected.

BJ Neff

Thanks BJ! Machine doubling can be very simple or in some cases, very weird.

[iloveikes]

1968-D KHD MDD Mintmark

Thanks for all the input...it IS a really cool thing in hand to observe, under magnification...like a stack of twisted pancakes...never seen anything like it as far as mintmarks are concerned. In hand, it's sticks up like a termite hill!
Cheers,
Cal