Silver coinage is very easy to discern and detect. It is heavier, and has a distinctive ring to it. But most telling are the edges. You can’t see any copper at the edge. If it were easy to counterfeit silver, don’t you think the U.S. government would have produced better looking coinage? There is another way to detect a 100 oz. bar as being silver. Suspend it with some string, or on a small canister, and bang it with a wooden spoon. It should ring like “riiinnnnngggg”. A lead filled bar would not ring.