I purchased this coin as part of a larger lot of random bronze artifacts from various periods. Most of it was junk, but there were some interesting pieces. I purchased in part because of the Tacitus Double Denarius which was identified by a fellow roman coin enjoyer in a forum that I posted to.

Below are photos of the Antoninianus (Double Denarius) are taken under microscope. When I saw these photos it becomes clear the extent of the green rock deposits and dirt embedded onto the surfaces of the coin.

I started by spending some time looking at the surfaces under microscope from different angles to better understand how to remove it.

I decided that it was too impacted for immediate removal, so I opted for soaking in distilled water. The first soak was 3 weeks.

After Photos