I am looking at a silver Roosevelt dime (1950-P, PCGS MS61) that is struck on a thick planchet of 54 grains (3.5 grams). The standard weight for a silver dime is 2.5 grams. How do I find out if the stock is actually wrong and was struck on a quarter or half dollar stock, or if the stock is correct for a dime but it is just thicker than normal, since I can't measure the coin's edge with it being slabbed? Since it weighs 1 full gram more, is it safe to say it is quarter stock? Will the slab always say "quarter stock" or "dime stock" or "half-dollar stock" and just "thin or thick" if the actual stock is correct, but the weight is off?
The weight of a dime struck on quarter stock would be the area of a dime divided by the area of the quarter. The only variable between the two is diameter, so we can calculate (17.9/24.3) squared times the quarter weight of 5.67 grams. I get .5426(5.67) = 3.077 grams. I have seen one example where a clad dime struck on clad quarter stock weighed 3.0 grams. However when you substitute the weight of a silver quarter (6.25 grams) the answer that the dime would weigh is 3.4 grams. So it seems very possible that this dime is struck on quarter stock.
Ok, but of it is a 1950 dime, the stock for a silver quarter at that time is 6.3 grams, not clad at 5.6. How would that change the equation?
Some of these type of mint errors are hard to say if it's rolled thick or thin vs. wrong stock. Can you provide a picture of the slab? There is also struck on foreign planchet errors.
Now I have to research if it is worth the $245 he is asking; kinda thinking "no" as silver quarters go for about $160 in MS. But then maybe there are more thick planchets on quarters than there are dimes. Anyone have an idea?
IDK but I would guess the opposite. That there would be more thinly rolled planchets for quarters, and thickly rolled for dimes. Paddyman might know.
I should read up on the minting process but my question is that if it was struck on a quarter planchet why would the weight be lower than that of a quarter?
Not struck on a quarter planchet, struck on quarter stock, a dime diameter blank punched out of silver strip rolled to the thickness used for quarters.