Question about coin weights

I was reading a post on a Reddit group (https://www.reddit.com/r/coins/comments/1j6uheh/did_i_get_lucky/)regarding a coin's weight and I am wondering what your thoughts might be. They were talking about the weight of a Morgan Dollar determining if the coin was legit or not. Based on the pictures of the coin, it was clear that the coin was a counterfeit coin. The color, texture on the coin, coin rim, and font on the coin were wrong. The OP posted the picture of the coin's weight showing it to be 24g. This got me thinking about one of my Morgans.

I have a 1880 O Morgan. From the fine people at CoinTalk I acquired a coin weight tolerance chart which said that Morgans should weigh 26.730 with a tolerance of 0.097 in coin weight. This means that Morgans should weigh 26.337g or 26.827g fresh from the mint. My Morgan weighs 25.36g and is heavily worn. Is it plausible that it lost nearly 1g worth of weight due to wear?

Yes, my scale is properly calibrated - just to answer that question.

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That chart has known inaccuracies. Use a Yeoman Red Book instead.

 

A Morgan Dollar can be rolled thinner or thicker than normal just as any other coin can. The chart you showed contains weights that are not correct. You should be using the Red Book for coin weights.
Given the coin you posted and it’s wear from circulation, if it was rolled on the lighter side it could be lighter than it should be. I’d have the scale rechecked. I see nothing that leads me to believe your coin is counterfeit.

 

Here's what I see from the first two heavily worn Morgans I pulled, along with one that has little wear. Looks to me like OP's coin is right in line with these.

 

Or even better, read the actual coinage acts.

 

Bragger.

 

In my opinion a coin could easily lose 5% of its weight (your stats) from that level of wear. The Morgan is 2.4mm thick. That means an average loss of 0.12mm in thickness. Picture how much a six-hundredths of a millimeter is, worn off from both sides.

 

When I was measuring coin weights, I found that well-worn Morgans usually lost well under 10% of their weight. Same with half dollars; to get below 11.5g, you had to be looking at a super-slick Barber (and I do have some of those).

But proportional weight loss increases the smaller the denomination, because it seems to be proportional to surface area, not weight. Smaller coins (or anything else) have more proportional surface area than larger ones. I found Barber dimes that were below 2g, a 20% loss.

 

And PROUD of it Doggo.

U. S. Monetary Acts from 1791 to 1873
(Library of Congress History Links)

https://www.heritech.com/pridger/monetaryacts.htm

 

I'll add "extensive survey of coin weight loss with wear" to the "Things to do in retirement" list.

 

Doug, the US mint would tend to disagree with you. This is a page from the 1902 mint annual report, where they did exactly this study.

 

Need to at least acknowledge the assumption that quality control at the mint works and that the coins in any study of loss-to-abrasion met the "standard" when minted and released into the wild.

 

I remember seeing this table previously, or ones like it. For numismatics, of course, we'd rather see it broken out by grades and types instead of by years. (Also, "loss per cent" in ounces? )

But, yeah, I'd be consulting references like that as well, instead of heading straight for the analytical scale. (Even though I'm always looking for excuses to use an analytical scale...)

 

Well, they did seem to take this stuff pretty seriously when coins were made of precious metal. And in modern times I guess they're still beholden to the vending machine industry - those machines need to know what weight/dimensions/composition to expect.

 

Agreed. But all assumptions must be listed in order to be taken seriously! lol

I assume you know that!

 

I only posted a snapshot of half of a page. The study in the full report has about 10 pages of data tables. You can read it here: https://nnp.wustl.edu/library/book/321

 

Pretty safe assumption since they were still individually weighing each planchet at that time and they had to meet the legal tolerances. Even when they went to automatic machine weighing, which I think was in the 1880's, each planchet was still individually weighed. Over and underweight pieces were rejected. In earlier year the overweight blanks would be adjusted (filed) to bring the weight down into tolerance. I don't know when individual weighing for silver stopped (probably in the 1920's) but I believe gold weighing continued through the end of gold coinage in 1933.