I bought a 1976 silver proof quarter a few of days ago and noticed that the mint mark looks sort of filled in. I can't tell if it's just frosted or an IDB. It's my first proof - are the mm's frosted by default? I can't find a good close up of the mm online. Pardon the clutter, I think (hope?) most of it is on top of the airtight it came in. Thanks for any insight.
I think it's just a very tight S for that year . Plus there is a reflection going on . If that makes sense .
@CygnusCC It looks normal to me. Click on the link and scroll down to the year. San Francisco Mintmark Styles (varietyvista.com)
Excellent, that's exactly what I was looking for @cpm9ball. Thank you sir. I was expecting something more on par with a modern mintmark where you see the field inside the S, instead of the entire letter being layered on top.