Good, I learned something. I right away assumed that a regular penny would be a big copper or bronze coin. In later years, the smaller silver Maundy pieces were struck.
Well I discovered this specimen really liked the look and was holed. I purchased this as a gift for a member here.
Just got this one. The edges are really banged up but it's still a neat looking piece. Iceland - 10 Kronur, 1930
25 Japan coins in a folder for $5 US; 20 cents each. Unfortunately the coins are glued into the folder.
I have bought glued coins like that before. I soaked them in water, and if that did not loosen the glue enough, then in acetone. Some did come out discolored from the glue, but at least I got the glue off.
I soaked a coin with distilled water and then bent the folder and the folder split and the 4 coins in the row popped out. Then after a 15 minute soak in distilled water here are a couple. Japan 5 Sen Showa 16 (1941) variety 1 (1.2 grams) Aluminum 19mm- unfortunately this one has a scratch on the obverse (which was facing out in the folder) that details the coin. This next one is a Japan 5 Sen Showa 17 (1942) variety 2 - 1.0 gr Aluminum 19 mm. This one has an interesting die crack across the bird breast and going to the rim around K-7. The obverse of this one was facing in the folder (with the reverse out).
Japan 5 Sen Showa 11 (1936) Nickel 19mm. If the distilled water soak doesn't work I will try acetone. Not sure what the green stuff is. Thought verdigris was mainly on copper/brass? This next one is Japan 5 Sen Showa 14 (1940). Aluminum - Bronze. I am I hoping acetone will help these 2. Actually see some luster on these 2.
Neat looking wartime coins. I have a batch of 20 on the way, all Japanese and I think mostly pre 1939. I will have fun sorting them out. I too am curious about the green spots on the aluminum coin. Probably some form of corrosion. A good soak in some non harmful solvent and perhaps some gentle picking with a wooden toothpick would help? I have used olive oil with success on AE coins, though I would not soak anything for long as it could be acidic. Wash well with soap and water afterward. I am ok with 'conserving' coins, not any sort of harmful 'cleaning'.