1923 Peace Dollar (Unusual)

Acetone is your friend. Suggest not scratching the coin. If possible, please post close-in, high resolution images. May help us better see what's going on.

Sorry about the pics...just using my USB microscope.

The rest of the coin is very unremarkable maybe EF-AU. When I first found her...thought it was nail polish...so she soaked in acetone for a day...and when nothing happened...I just threw her in a flip.
Zoomed in on the only area in question that looks similar to Kahawais' coin...if I run a toothpick over it...from the silver to the copper/pinkish color...it drops down.
she weighs 26.7g
From the side pic...almost looks etched? maybe some kind of acid...idk?
Well that's what I got...






Lets hear what it might be...?

smat

I already did the acetone bath...but nothing happened...?
On the side pic...if you were to gently drag a toothpick from the edge to the area in question...it would drop down (incuse)...it's not raised on the surface.
I'm just responding to Kahawais' post about a similar Peace dollar that I have. I was questioning if maybe there was a chance that there may have been some sort of improper alloy mix (Thanks Mr Frog...I called it "like a lam" peel) since the area is not raised...?
Maybe some kind of acid...idk? But when I saw his coin it reminded me of mine...and both being San Francisco mint marks kind of made me think of any correlations between the 2...?
Let us know what you think...
smat

Thanks for the replies...acid does make sense.

I just find it interesting that both our coins are from San Fran and have random large incuse "pitting"?

I think it's just a bullion coin now too...last year when Ag was down I bought a couple of rolls of random dates for $17 apiece and this was in there hidden away.

She's in a flip and I'll just keep an eye out on the board to see if any similar Peace dollars show up to discuss...?

smat