I think this is a nice original condition toned example of an 1896 Morgan Philadelphia mint dollar. The reverse was taped at one point. How, why, where I don't know, but on the reverse you can clearly see two distinct tape marks. One going north/south, and the other across the eagles wings. The coin has been dipped in acetone to remove the glue, and what you see now is not glue but natural aging and toning that occurred at different rates depending on what part of the coin was exposed to the environment, and what part was under tape.
I graded this when I acquired it around 4 years ago and looking at it Now I'm wondering if I may have been low and it's nearer a 58.
This coin was dipped at one time (dipping isn't considered cleaning), but then was mishandled. The mishandling is the issue. Notice the fingerprints on the left side of the obverse and reverse.
The coin was likely stored in a Kraft envelope. It was common back in the day to place gauze pads on either side of an envelope coin to prevent the sulfur in the envelope from harming the coin. I suspect the gauze pads protected parts of the reverse in the envelope, but created the appearance seen today.
Still a nice coin, but it needs some conservation. The fingerprints probably are permanent.
This one is very close to MS if not MS. The only issue I see the the tone which may or may not be hiding any circulation marks. Worst case AU-58, best case MS-64. You'd need this one in hand to know for sure.