Ok Skippy, I took it out of the holder. I was going to do the aluminum thing, but when I tried it on a merc, it did not work for me, so I'll have to practice or something.
Anyway, I weighed and measured to compare dimensions to a dime and they are very similar.
The weight on the Rosie bounced from 2.4 to 2.5 g., and the "silver cent" stuck at 2.4g.
The thickness on the two was virtually identical 0.044 for the cent, and 0.047 for the Rosie.
The diameters varied some, but if a dime planchet was used in cent dies, it would expand to fill the die, so it should be larger 0.729 for the "cent" and 0.701 for the Rosie.
I examined the rim of the "cent" and it is not smooth. I really don't know how to properly describe it. It shows some evidence of metal flow, it is not uniform. The brownish staining on the rim, as seen in the two images, seems to rub off, it is not another metal. I rubbed part of it off after the images were taken, but did not notice it until I saw the photos.
I really don't know what it is, maybe someone can figure it out. Lustre/color on the two coins is not exactly the same either, but the "cent" has been in a holder ever since I got it, or as long as I can remember anyway. The other coin has been handled, actually came out of the ground last year, so that would make some difference on coloring.
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Edit: I tried being more patient with the spit test on silver, and got a result.
So I tried it on the silver colored cent and it didn't smell of sulphur: so it is most likely not silver. It is more shiny now
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Pics below.