Here is a pile of Roman silver coins. I put them on a scanner and hoped for the best. Well as you can see with Roman coins there are and was the good, the bad and the ugly. What is most fascinating with Roman silver is that they were only made by the Government of Rome, not the provinces. In the provinces they would make bronze coins. In the early days of Rome, these coins were worth more as a coin than the material they were made of. As Rome started to fall slowly the content of silver started to as well. It became a mess in the later years as many silver coins had little real silver in them. Here you will see a pile of silver coins from ancient Rome. Some look much more silvery than others. That is due to time and also to content. In fact in its later days, the Roman silver coin was just coated with silver. I have found many coins like that, in the coin world they are called silvered.
I am not going into any great detail here, but as I often like to do is spur your interests and get you to study. But if you look as a correlation of times the sameness of American coins. Once they were pure silver, then in 1965 they were made of copper and coated with silver. That is what our silver coinage is today. Not really silver, just a touch of silver.