I decided to go ahead and spawn off a new thread where I'll post photos and high-resolution (10mg or 1mg) weights of coins in various states of wear. For now, I'll just be posting as I get and/or weigh things; later, I hope to put all this together into some organized format. Tonight's subjects are 15 SLQ's that I recently landed on eBay "below spot" -- at the time I bought them, Coinflation was quoting quarters at just about 20x FV, or $75 for 15, and I paid $68 with shipping for these. Nominal weight for 15 quarters as minted is 15 x 6.25 = 93.75g. These, though, range from G04 (there might be one that reaches G06) to PO01 -- pretty sad shape, but pretty typical for bulk circulated SLQ's. Here are the coins (obverse and reverse): Here are the weights: 5.96 6.06 5.97 6.03 5.88 5.80 5.96 6.00 5.79 5.84 5.66 5.81 5.75 5.75 5.59 Total weight: 87.85g. If 15 full-weight quarters contained $75 worth of silver, these would contain $70.28 (ignoring the probably-negligible weight of tarnish and debris they carry). I'm still ahead, but the "wear penalty" on these coins was about 6.3%.
This is a good "average" determination, but such an exact loss could not be accurately determined as each quarter may have weighed differently in mint condition. This was due to the tolerance of the quarter weight as 6.25 grams Plus or minus 0.097 grams. So a newly minted quarter could weigh from 6.153 grams to 6.347 grams, the average could be assumed to be 6.25 grams. Not knocking your experiment, just saying the tolerance makes it tough to determine wear penalty.. Jim
Wow, I thought I'd be doing a little better at getting new material posted here... I wanted to do a quick snapshot addressing the "height of a stack" question. People have observed that you can fit more (say) worn Walking Liberty halves than Kennedy halves into a coin tube. How much "thinner" do coins get as they wear? Here's a comparison between a stack of nice 1963-1964 quarters, a stack of well-worn Washington quarters (mostly from the 40's, a couple of AGs, most G-VG, and a few F), and a stack of well-worn to dateless SLQ's (the kind that make it into junk silver lots). Each stack contains 20 coins. Heights: 27+ mm, 31 mm, 34mm Weights: 116.35 g, 122.12 g, 125.35 g So, yes, those stacks do get distinctly shorter with wear. For the Washington quarters, a full roll of worn ones would be about "four quarters" shorter than a full roll of AU/BU. That's about 10%. The SLQ's are shorter still. But the weights don't decrease nearly as quickly. That 10% "thinning" of the Washingtons corresponds to a mere 3% loss in weight, and even those slick SLQ's, 20% "shorter", are only down about 7% in weight. This isn't really surprising. Wear takes down the high points of the coin first, and those high points determine the spacing of coins in a stack. (I don't have enough well-struck examples to do a comparison of different uncirculated types, so I still don't know whether full-strike Walkers stack more or less densely than Kennedys.) I should probably do the same comparison for Mercury dimes, which get really slick and lose proportionally more weight with wear. I have a stack of pretty nice uncirculated Mercs now (not slab-worthy or FSB, but unworn), and quite a few BU Rosies, so I can do the between-type comparison there as well.
