Congrats on your find...and an AT Pro with a 5x8 coil is an excellent choice! My detector and coil of choice. Now, be careful about cleaning silver coins. What I mean is...you'll get a variety of opinions on cleaning silver coins; some will say just use running water, while others will use a Dremel. A "cleaned" coin is generally worth less when selling it on the open market, but shiny ones can look cool. I only say this since your Merc looks polished with silver cleaner (man, I do know how to pop party balloons). Really, WTG.
NICE !! I myself plucked a nice 39 Merc from Mother Earth yesterday, a short, unplanned hunt in the NEIGHBORS yard! ha..I had dug too many wheats there not to have found silver..and yesterday produced silver for me too...awesome looking coin! and many congrats..you are definitely hooked hard..ddf