Advice

I'm a beginner metal detectorist and regularly find coins in this condition. Can these still be cleaned? Or what's the best thing to do with them?

And is such an electronic microscope with lcd display from eBay/temu a good purchase for this?

 Any advice is welcome.

The topic of coin cleaning is often raised on Numista. It's good that you ask before doing anything. There are various views on this, and it depends a lot on what one means by “cleaning”.

The goal in most cases should be to remove any incrustations on the surface, but as much as possible let the patina or toning stand as is. This is not always possible and for some ancient periods, coins are sometimes entirely cleaned, such as many Roman silver coins on the market.

Some people trust only “dry” methods whereby you carefully scrape off any dirt or incrustations as long as you don't “dig” into the coin. This digging can easily happen in the case of Roman bronze coins where the corrosion has penetrated into spots on the coin. In such case, you have to know when to stop and proceed with a treatment that will stop any further degradation.

Some others believe a bath in olive oil is harmless and will take care of most the surface dirt. The advantage with this method for low grade and low value coins is that it's easy, cheap, and much less time-consuming than the dry method. Here are a few slides I used to document my experience (for a lecture on the basics of Numismatics):

1. 2. 

3. 4. 

5.

I let the coins soak for a couple of weeks (2). Even though it probably made no difference, I turned them once in a while, actually checking whether it was time to remove them. Once I took them out of the bath, I removed all the oil with a soft dish washing liquid in a sponge (3). I didn't want any oil to be left on the surface — and remember, these are virtually worthless coins; I would have been more careful with a rare and expensive coin. I think the result was positive (4). We can now identify some of the coins (5). While a coin collector would not normally care for such common, low grade Late Roman coins, there is much fun in trying to identify them. It's also a great way to learn more about Roman coins and become familiar with the catalogues in this field (RIC and online catalogues such as OCRE).

Some of your coins could go through a first cleaning with just water. From there you may decide to proceed with a more thorough treatment. Several of the coins could be identified before any major cleaning, and from there you may decide that there's not much risk in trying the olive oil method or else to leave it to a more experienced collector if the coin appears to have a certain value. In some cases, the side which you show is not enough for identification, but possible the other side will help. For example, on the photo of six coins I can't say much about the first on the second line, but I suspect it's Roman. Any features left on the other side? If not, it's probably unidentifiable.

thanks for the info 👍🏻