...or dime, and look at the edge of the coins. You'll see a copper center layer and a layer of 75% copper/25% nickel on either side. The two outer "clad" layers are the same material they make nickels from.
When the mint decided it was too costly to make coins out of silver they went to the "clad" composition. That was in 1964. No American coins intended for circulation have been made of coin silver (90% silver) since then. There were the "clad silver" Kennedy halves, which were 40% silver, but they ceased being minted in 1969.
SO, now you can see why detectorists get all excited over a little silver dime or quarter:
A. It's old
B. It's pre-64, ie, genuine silver
By the way, U.S. one-cent coins ** are no longer made of copper either. That stopped midway through 1982, for the same reason - too costly to make. They are now a zinc core, coated with a copper wash. Since they're made of what are called "ignoble metals" they dont hold up well against the elements.
You'll find 100 year old cents that are stil hale and whole and five year old "zincers", as the new one's are called, which are half eaten by corrosion. Bill has been moaning for years over the fact that our coins are little more than tokens any longer. I remember reading his stuff years ago and recall him saying it then. He's right, by the way. A Chuck E. Cheese token has more intrinsic worth than a U.S cent.
**(U.S. Cent is their rightful name - there are no "pennies" in the U.S. coinage system. That's from the English 'Sterling' system and is a holdover from colonial days when English coins - as well as those of other countries - circulated freely on these shores. Pull out a "penny" and read what it says on the back: One Cent.)
