Any Idea What This Is? (Id: Counterstamped Brazilian 80 Reis)

To the CCF

Please rotate and crop your picture as CCF instructions when posting.
Also show complete coin along with dimensions and weight.

Thanks for all of the responses. Here is another image with sizing. It weighs exactly 1oz. I cannot make out any of the lettering.

As oriole already mentioned, this is a Brazilian coin of 80 reis with a counterstamp to make it a 40 reis coin.
I am afraid it will be impossible to read the date on the host coin.
https://en.numista.com/catalogue/pieces3974.html

Sorry I can't contribute but I bet there is an interesting story here.....

These aren't particularly valuable even in better condition; with no indication of the host coin's date or mintmark, there's minimal value to a collector, except perhaps a "countermark collector" who just wants a cheap example of these official government counterstamps. The green blotches will also be off-putting to a collector.

The original coins have a few interesting points. Notably, that different provincial mints in Brazil issued the same denomination in different sizes and weights, depending on copper availability, hence the need for the subsequent government counterstamps. The catalogue also notes that the coins were extensively counterfeited, to the extent that modern collectors don't know, or even particularly care, whether a specific coin is counterfeit or not. Both counterfeits and legitimate coins would have received the official government counterstamp and put back into circulation. Given that the counterstamp on this particular coin is not very well worn, I suspect the original coin was quite heavily worn when it was recalled for counterstamping.