I acquired two samples of metallic cobalt from China for my chemical element collection.
They are 99.99% pure electrolytic rounds/buttons supposedly used for steel making and other metalurgical purposes.
As the samples appeared to be tarnished and covered by a dark grayish substance, I used a special dishsoap, based on this Dodecylbenzene Sulfonic Acid.
Immediately, all the gray/black stuff started coming off the surface of the cobalt and made my fingers dirty.
Both samples are now perfectly clean and the cobalt looks very shiny/lustrous.
What reaction took place here if any? Just curious, thanks in advance.