Percentage of a coin's mass actually worn off

GoldenEyeNumismatics

I've always wondered if, when a coin is worn to AG-, how much of it's metal has actually been worn off. I only tested it for Silver dollars, but what I came to was about 7%. So an AG Morgan Dollar has about 93% of it's original metallic mass, despite being much thinner. I guess a lot of the "wear" is just the metal being pushed around, and not actually being removed.

fc

i can tell you that a roll of worn mercury dimes is much smaller
then a normal roll of modern roosies. this tells me a significant
amout of wear has taken place.

but how much less does it weigh? i am unsure as i do not have
a scale. I like your unformal test and think 7% is a fair estimate.

i wonder what others think. cool post.

GoldenEyeNumismatics

<< <i>i can tell you that a roll of worn mercury dimes is much smaller
then a normal roll of modern roosies. this tells me a significant
amout of wear has taken place.

but how much less does it weigh? i am unsure as i do not have
a scale. I like your unformal test and think 7% is a fair estimate.

i wonder what others think. cool post. >>



I think that, for the most part, the thinness of heavily worn coins can be attributed to the loss of their rim.

Artist

7% is a big number.

On an AG coin, only the devices are worn smooth - the fields (and all the metal behind them, which is the majority of the coin) remain intact.

In addition to Mercs, I have heard that rolls of SLQs are also noticeably shorter when worn - in such cases, when the high points of the coins are worn down they sit closer to together, so there is less air between coins.

By the way: neat experiment!

MrHalfDime

I maintain an extensive database of my reference collection of half dimes, which presently contains 1820 half dimes of all series. One of the pieces of data that I keep detailed records of is the weight (mass) of each half dime in my collection. Now, to be sure, a half dime is significantly smaller than a Morgan dollar, and I have no data to compare the loss of silver due to circulation wear of a half dime when compared with a Morgan dollar, but I can tell you, with some authority, about the loss of mass for half dimes due to circulation.

The Flowing Hair half dimes (1794-1795) had a specified weight at minting of 1.35 grams. Similarly, the Draped Bust half dimes also had a specified weight at minting of 1.35 grams. Also the Capped Bust half dimes had an initial specified weight of 1.35 grams. The Liberty Seated half dimes initially had a specified mass of 1.35 grams, but that mass was reduced to 1.25 grams in 1853, when the weight of silver was reduced to reflect the increasing cost of silver. These are designated by the arrows at the date.

In my database, I show many half dimes at 1.35 grams, and ranging down to 1.13 grams in G-4 grade. Most of my half dimes are EF-AU-low mint state, so most are pretty close to 1.35 grams, but several are more circulated, and exhibit proportional weight loss. For this comparison, I excluded any clipped or incomplete planchet half dimes, any love tokens which had metal purposely removed, and any counterfeit half dimes.

A G-4 half dime weighing 1.13 G has suffered a weight loss of 0.22 G, or 16% of its mass! That is very significant.

I also looked at half dimes with more than the specified weight. This, of course, would be due to inconsistencies in the planchet adjustment room, and not due to circulation wear, but I thought it would be interesting to look at. I have examples weighing as much as 1.42 grams, or 5% above specification, although any half dime weighing above the specified 1.35 G weight is quite rare.

au58

<< <i>i can tell you that a roll of worn mercury dimes is much smaller
then a normal roll of modern roosies. this tells me a significant
amout of wear has taken place.

but how much less does it weigh? i am unsure as i do not have
a scale. I like your unformal test and think 7% is a fair estimate.

i wonder what others think. cool post. >>



I have a roll of early date Mercury dimes, mostly AG-G. The roll is only about 80% the length of a standard roll.
But I don't think 20% is gone. The rims (a small percentage of the total mass) have done their job and protected most of the coin.
And a lot of metal does get moved around. 7% is probably in the ball park.

fastrudy

I was surprised when I massed a Barber Half in fair condition. 92% of the initial mass was still there. Worn Merc dimes are so thin, but not a large loss of mass. When silver was super hot, BU dimes and worn mercs brought the same premium over face and went into the same melting pot.

Deadhorse

On average, using circ coins, I have consistently weighed $100 bags of Roosevelt dimes to be in the range of 2,490 grams, give or take a couple of grams.

With circ Mercurys, just grabbed from larger bags at random, they come in at 2,435 grams. Again, give or take a few grams.

So........ for what it's worth, it would appear that less than 3% metal that has been lost. With $100 dollars we are talking about 2 ounces or so. 90% of that being silver. As with most Merc dimes, the bulk of them in melt bags are dated in the late '30s and the '40s.

While I haven't weighed them by roll, I do know that a roll of teens and '20s Mercs, compared side by side with average '50's Roosevelts appears to be short by as much as 5 dimes or more, that would put the wear/loss factor somewhat higher than 10%.

This is not a scientific analysis by any means. I have only weighed out a couple of hundred $100 bags, so my population sample is probably too small to considered as solid evidence of anything. Just a bit of food for thought from my experiences.

Frankcoins

Seldom does a specific silver coin lose even 5% of its weight, while mixed circulated $1000 bags are usually no more than 10 ounces (1.5%) light.