We were planning of visiting a coin seller in Texas as part of a larger trip. This fellow had about $4,000 face value of Lincoln Wheat Cents and a small quantity of silver Dollars, one of which was a decent 93-S.
The problem was that he had read somewhere that copper ancient coins were sometimes preserved in olive oil. So he had places the pennies in various plastic containers and immersed them with olive oil. We weren’t sure what we might do with the pennies but we figured we could look with an open mind.
Unfortunately we didn’t see him. A few days before our scheduled visit he decided that the silver dollars weren’t shiny enough, so he used a metal polish on them to clean them up. He said he paid special attention to the 1893-S as he knew that was a valuable coin.