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Anyone Have The Thickness Of The .999 Comems Like Mcauliffe Or Womens .

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Pillar of the Community
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1431 Posts
 Posted 04/13/2021  4:48 pm Show Profile   Bookmark this topic Add Big-Kingdom to your friends list Get a Link to this Message
Hi sorry if this is asked or common knowledge. I'm doing some sluthing.

I don't find the thickness for any of those commems anywhere. I'm suspecting these.999 blanks are the ones that will be used for the Morgan and Peace dollars, and the specs that are available say they are 1.5 inch diameter, 26.73mm.

They can't rob from peter to pay paul, for sure those commem dollars aren't 1 troy oz, but I'm wondering if they compromised from thickness or if just removing the copper is that difference from the .900 blanks that were used, I think those were called T-1 blanks.

So, anyone know the answer here? I doubt they are 2.4mm thickness. but the diameter and weight is right for a morgan.
Edited by Big-Kingdom
04/13/2021 4:53 pm
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United States
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 Posted 04/13/2021  5:46 pm  Show Profile   Bookmark this reply Add Numisma to your friends list Get a Link to this Reply

1.5 inch diameter, 26.73mm g

These are the same stats as a Morgan or Peace dollar.

The densities at room temperature for silver and copper are 10.49 and 8.96 g/mL, respectively.

A 90% silver (by mass) dollar therefore has an ideal volume of 2.592 mL, and a pure silver dollar of the same weight is 2.548 mL. The 90% coin should be about 1.708% thicker. Given the 2.4 mm thickness listed, there's essentially no difference given significant figures. That said, it could vary depending on relief. I don't know if that figure is the maximum thickness or the calculated average thickness.

Edit: the average thickness of an ideal silver dollar, i.e. height of a cylinder with volume 2.592 mL and diameter 38.1 mm, is 2.273 mm. I'm confident that the 2.4 figure is probably for the maximum height and therefore should vary by relief height.
Edited by Numisma
04/13/2021 5:55 pm
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1431 Posts
 Posted 04/14/2021  10:33 am  Show Profile   Bookmark this reply Add Big-Kingdom to your friends list Get a Link to this Reply
Ok, so, generally speaking, there should be no difference in thickness between a 90% Morgan dollar, and a 2021 McAuliffe comem. Both have same diameter, same weights, one is .900, the other .999, and while there may be some slighter thinness, it's going to be an imperceptible 0.127mm difference tops thinner

in comparison the difference of the silver eagle 40.6mm vs. the Morgan dollar 38.1mm is the diameter and weights, and I'd assume the copper weight as a filler material.

With the .999 comem blank, I'd have to assume at 38.1mm diameter and weight of 26.73g, It's clearly not one oz of fine silver. it's more than the silver content of a Morgan dollar though which has 24.05g of fine silver weight.

in other words, the .999 comem blank is thinner than a Morgan dollar, but it's so slight (1/8th a millimeter or 127 microns to be exact), it's not going to be really noticeably thinner, but because of .999, it will have slightly more fine silver in it than a Morgan dollar does by 2.68g.

I think I get it. Seems like there would be a big difference at face value but seems like it's a really small difference.
Edited by Big-Kingdom
04/14/2021 10:53 am
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