Uruguay: 10 pesos 2015, KM134, alloys?

N#22257

I just got those in a swap, and the alloys in the inner circle look different from each other

Can anyone confirm that? Maybe it's just my eyes!

Well there is definitely a colour difference (assuming same lighting, etc), which I am sure you have done.

I wouldn’t say that one is copper though, maybe it’s just a case of different copper to zinc? ratios of the Brass over the steel?

Or maybe the royal mint used a bag of blanks that have been environmentally altered through discrepancies in storage.

Definitively some surface stuff going on.

I used my 1200dpi flatbed scanner for the images. So same lightning.

I also noticed “spot” on the obverse of the non brass coin. On the reverse (the jaguar) there are no damages.

I'm not insisting on anything, I just found it interesting, and I have seen that before on other coins from different countries and I tend to believe, that two different alloys have been used, maybe they should be named light brass and dark brass?

There are others, but I have lost the trace of them!