It's chemical because you have to heat a liquid until it's super hot then you put the penny's in a cooler liquid and then it changes color.
Molten zinc or gallium will turn cold when you put a penny in it because they have a lower melting point than the metal in the penny, causing the penny to rapidly transfer its heat to the liquid metal and cool down.
liquid
magma is hot liquid rock that makes what power possible?
In this case a solution is formed.
vinegar, soda, and water after 2 weeks
The diamond was the shiniest jewel I had ever laid my eyes upon.
penny
Generally, you can find the shiniest diamonds at the jewelery store, because only 20% of all diamonds mined are gemstones..
The superlative of "shine" is "shiniest."
The superlative of shiny is shiniest.
shinier, shiniest
Shiniest
oil
shinier shiniest
Shiniest or most shiny.
The root word is shiny