Tough one for sure. If I'm seeing it right, I bet it's something foreign we'd never think of. Here's the type of bust I see, only facing the opposite way. This is in no way a guess or suggestion, I just am familiar with the early Belgium coins having that shape of bust and found the pic to show you.
Thanks for your input, IP. I just posted the coin in "What is it?"
Certainly silver, and looks like it was struck with a collar, not hammered. I looked through British and French and didn't see anything close. I don't think anything spanish makes sense, but my gut feeling is late 1600s or 1700s.
After looking at your suggestion, I am wondering if you think that the first photo is the bust side. The second photo is, and it is upside down, now corrected in my "What is it?" post.