I love Japanese currency, especially the 5-yen and 50-yen pieces–easy to find in my change purse and just fun to touch. Rocket News 24 has an article about the history, designs, and make-up of Japanese coins.
Like many small currencies of its type, the one-yen coin costs more to make than it’s actually worth. The amount of aluminum used alone is worth 0.7 yen (US$0.007), so after including all the other overhead you’re looking at about 2 yen ($0.02) a coin to produce.
The pure aluminum used gives this coin some unique properties too. First, it might be the only coin that floats on water. Actually if you were to toss the coin or push it down with your finger it would easily sink. The density of the coin is not buoyant, but its light weight allows the surface tension of the water to hold it up.
Read the full article here.