I have always heard that there were 3 accurate weight standards out there... a brand new un-circulated Jefferson nickel at 5.000 grams, a post 1982 penny at 2.500 grams and any brand new un-circulated US currency bill at 1.0 +/- 3%. When you get a stack of new bills together, that +/- evens out pretty well, so that a stack of 50 bills is usually pretty dead on 50 grams, but within the printing office standards there is room for that stack to potentially be between 51.5 and 48.5 grams. It is easier and more accurate to go to your local bank and get new nickels or pennies though... and certainly cheaper than going out to buy a 50g standard weight at some hobby/science store.

All of the coins have changed drastically over the years. Pennies have had steel and aluminum in them, silver has been used in some coins over the years but no longer, the copper content of pennies has changed drastically until today they are simply copper plated zinc. The nickel is the only coin we have that actually uses 25% nickel in its mixture and this is why it is so carefully measured. The rest of the common coins in use today are a mix of 8.3% nickel and the rest copper.

Emmie