The theme of my collection is coins of various names and denominations. I already have samples of over 500 denominations.
Among them is this interesting assarion (Bosporan Kingdom, from 39 to 45 AD): approximately Panticapaeum Mint — modern Kerch (Crimea, Ukraine):

This coin stands out among other ancient coins in my collection with some strange "golden" coating.
Who has reliable information about what this could be? What is the reason and circumstances of the appearance of this "goldenness"?
Unfortunately, I can find very few high-quality photos of coins of this type...
All the detailed information about this coin that I managed to find is on my website:
https://www.dema-coins.com/2023/07/...capaeum.htmlAt one time I described this fragmentary golden sheen as traces of the used aurichalcum (highly valued alloy composed of copper, zinc, nickel, lead, and iron), but the other day I looked at the coin in more detail and had doubts. Is it possible that there are traces of real gold on one side of the coin? (I do not have the technical ability to perform the analysis)