HI Bill...
I have this coin in my "to do" pile, ( which is actually larger than my documented and researched
collection...
) ....I would think it is from a similar period as your coin... In hand it shows many of the same attributes as your coin, brown patches which I have put down to a very low silver content rather than it being a
fourree...
Don't break your coin! Official or not, looking at it I'm almost 100% convinced the coloration is due to a crappy
alloy mix rather than it being
plated!!!
Best wishes,
Lee.