Looks like its seen some heat at one time? No numismatic value, SO it's still an ounce of silver. May have collector value, I'd leave it be. If you sell it, let the next guy dip it if they care to.
Don't dip it. Your coin is listed in the Catalog of Unusual Coins under U.S. There is a 1, 2, & 3 oz Piece listed. 1 oz is X#4. $45.00 in XF / $65.00 in BU. Nice coin.
It's .999, so it's pretty reactive. And it's 45 years old. I wouldn't automatically condemn it as AT.