Is there a logic board schematic available for the A1347?

As I was taking apart my Mac Mini Mid-2011 to add a second hard drive, I managed to knock a piece off of the logic board. Fortunately the computer still boots and seems to function, though I understand that the small piece I knocked off most likely played some role in my Mac Mini's logic board. I googled around a bit and read the ifixit teardown but couldn't find a description of what the logic board components do except for some of the more exciting chips. Can someone point me to a guide or explain to me what a particular part of the logic board does? The component in question is a small silver circle with a bit of purple on it and is the top most in a cluster of three near on the bottom left (adjacent to teal square) portion of the logic board.

Here's an image of the side of the logic board: Mac Mini Mid-2011 Logic Board