1971-D Kennedy Half Dollar - Silver?

11.2 oz. I don't think so. That would be as heavy as a package of Ham. LOL You mean grams.

To this coin looks like glue is coating both surfaces of the coin?

and an accurate weight - I doubt it's 11.2 oz.

A little more info might help. Thanks, Doug.

Testing specific gravity of a coin is quick and easy. Here's what you will need:

1. A scale that reads to .01 grams or better. Since specific gravity is a ratio, it doesn't matter if the scale is accurate as long as it is precise.

2. A small plastic cup, preferably hard clear plastic. A plastic kids juice glass works fine.

3. A foot or so of thread.

4. Water. (I prefer distilled water, just to protect the coin a bit.)

Step one: tare the scale (manually reset it to zero).

Step two: weigh the coin while it is dry. I weight it once, tare the scale again and weigh it a second time. The weighings should be no more than +/- .02 apart. If they are, something went wrong. In that case, tare the scale again and weigh the coin again. Write the weight on a piece of paper.

Step three: fill the cup with enough water so that you eventually can dangle the coin in the cup with the water fully covering the coin without the coin touching the bottom or sides of the cup.

Step four: tie the thread around the coin so that it holds the coin securely and you have enough length of thread to suspend the coin in the water and hold the thread securely.

Step five: Place the cup with the water in it on the scale and then tare the scale. The scale should read 0.00.

Step six: Carefully dangle the coin in the cup, entirely beneath the surface of the water, without the coin touching the bottom or sides. The scale will settle on a reading. Write this number on the paper.

Step seven: Arithmetic time. Divide the Step Two number (dry value) by the reading from Step Six (wet value). Double check the arithmetic. The resulting number is specific gravity of the coin.

There are also hundreds of YouTube videos showing how to obtain and compare specific gravity of coins.

As a side note, if the issue involved a 90% U.S. or 80% Canadian silver coin, two other tests -- the "ping" test and an eddy current brake test -- can corroborate or rule out silver. These tests could slightly damage coins with numismatic value, however.