no luck, lol, i looked through every currency that was listed in the wiki for the time period of 1500-1850 and i couldnt find anything about it but a few things really keep jumping out at me, 1. I cant find any info on any spanish coin that was only struck on one side, ive went to google now and looked through a bunch of *treasure shops* and none of them mentioned it 2. its miscolored compared to all the silver spanish coins ive seen.3. the shape is very unusual and the only ones i saw with it was made before france took over for a while.4. all spanish silver minted in the new world ive seen have had proof marks somewhere on them, yours oddly do not. I'm still looking cuz i really want to find out, lol, but im getting less optimistic after each hour of fruitless looking. Maybe you got something super rare there or maybe a reproduction?(doesnt mean it has to be a recent reproduction of course)