Greetings! I have been collecting US coins for about a year. I inherited a large collection of coins from my dad and while sifting thru the hundreds of mercury dimes I saw one that immediately stood out. Its 1/2 gram lighter than the typical merc dime (this one weighs 2 grams) and is definitely not silver, what the metal is I'm not sure (zinc? tin?). It also makes a different sound when jingled with other coins. It is stamped 1943 D and looks to me to be a counterfeit. This picture is it laying on the scanner bed with the highest resolution I could get it, just a weird looking coin. A curiosity for sure....
Looks like it may have had an acid bath. Don't think that would take away a half gram. Poor quality cast copy? Interesting coin.
My first inclination is that this is a heavily corroded coin, possibly environmental damage from acidic soil. Often corroded coins do weigh less (but I don't think half a gram... is your scale accurate to at least tenths of a gram?), and will make a "different sound when jingled". Are you 100% positive it isn't silver? Common coins such as this are counterfeited less often, as the numismatic value is low. Possibly a contemporary example (poor quality as Larry mentioned), but I'm still leaning towards damaged.
