I've got some a lot slicker than that. I'll try to remember to dig a few out, photograph them, and weigh them. Since halves are so large, their surface area/volume ratio is lower, and they lose weight more slowly for a given level of wear. I'm guessing even my worst ones haven't lost much more than 10% of their weight. I've weighed slick Barber dimes that were under 2 grams, a loss of 20% or more.
Where do those silver atoms go, that wear away from silver coins? In your skin? Air, ground, water? And then, what do the released silver atoms attach to?
There was a trial that probably involved seated liberty dimes back in ca. 1894-5 where some municipality was refusing very worn coins on the trolley system. In the end the municipality lost the case, even though the coins had lost some 15-20% of their metal weight they were still regarded by the court as legal tender.
People used to "sweat" precious-metal coins -- put them in a bag, shake them for a while, and collect the dust. Since worn coins traditionally trade at face value just like new ones, it was a natural thing to try. I do think people actually got prosecuted for it, because fraudulent intent was clear.
That is a practice that dates back to ancient times, probably only went away with the cessation of silver in coinage.
A better trick for people to do was to get new silver and shave filings off the edges. Not enough to notice really, just like the coin would be in a year or so of circulation. There were stories of men gaining a dollar or two a day doing this, not bad considering well above a normal day's wages back then.
That reminds me about the stories of those old bankers who would collect the empty coin bags and burn them, then sift throught the ashes searching for any bits of gold and silver.
Preventing this is the precise reason why silver and gold coins have reeded edges. http://blog.littletoncoin.com/reeded-edges-american-coinage/
Silver will readily react with some sulfur compounds to produce a very thin outer layer of what we call toning (silver sulfide). This reaction is enhanced by heat and moisture but may require a catalyst, I don't know.
Yes, of course. Wording or reeds have been placed on coins since the invention of the modern presses. Clipping, (as it was called in ancient times), is much reduced because of reeding but not eliminated. Anyone who has handled a BU coin can tell you the reeding can be very sharp and pointy. Getting a back of new coins from the bank, "shaving" the reeds down to what a coin would be like when circulated, and then spending the coins at face value can net entrepreneurs a little but of PM for "free". I have circa 1800's coins that are full BU and very thin, cut down reeding on them. You would say the coins is BU and the reeds VG based upon their appearance.
As a general rule, stress general, coins do not really lose any weight to speak of due to wear - or put another way, not enough to take them out of tolerance levels - until they reach the stage of VG grade or lower. Now some folks have hard time believing that something like that could be true. But it is. That's because the metal doesn't really get worn away and removed from the coin in the beginning and intermediate stages of wear, it gets squished down, flattened out - moved from one place on the coin to another place on the coin. Take this coin for example, and it's gold which most think is much softer than other coin metals and thus more susceptible to wear - (which is not really true by the way). But most people do believe it to be true. Anyway, the coin - Now what do you think that coin would grade given that much wear ? I think everybody here is quite familiar with how much detail is supposed to be on that coin, and it's pretty obvious how much detail is NOT there. So what do you think it would grade ? Myself, I put it at no better than a F15. Now would you care to guess how much weight it lost at that point ? And I'm not going to provide the answer right this minute, I'm going to let you guess first
I'm going with "almost none". Even though it's a large coin made of dense metal, I'll bet the loss is less than 1% (.3 g).
People grossly overestimate weight loss, both in coins and bellies. I'll say less than 0.5% reduction.
I hate to resurrect yet another zombie thread, but this one left us hanging and I'd like to know the answer. My guess is 0.1gm.