1976 quarter silver proof - Is this mm frosted or idb?

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.

 

Log in or Sign up to hide this ad.

I think it's just a very tight S for that year . Plus there is a reflection going on . If that makes sense .

 

That sounds reasonable. Thanks for the input, Sal!

 

@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.

 

Yes, the mint marks are frosted as are all areas of relief. The fields are mirrored.