Jason in Enid said:
If you aren't sensing the sarcasm here, yes silver is that soft. Dirt contains sand. When you rub the dirt off a coins it is just like rubing sandpaper across it.
True, most silver coins aren't going to be affected by the small added scratches but a few can be and if you rub them all then it's too late when you find out you just reduced the value of a key-date coin.
When I found this quarter, all I could see through the clump of mud encasing it were one or two stars
and a sharp reeded edge. I wrapped the coin (mud and all) in a wet leaf and put it in a pill container.
When I got home, I ran it under tap water and with a Sable watercolor brush, GENTLY dislodged the
remaining dirt. If I had field-cleaned this coin by rubbing it between my fingers, it would have been a
numismatic disaster. Also, it gave me something to look forward to on the way home