Dang it. Apparently this is what happens when your 18th Century china taps the granite countertop in just the wrong way.
I could be devastated and flagellate myself for not having wrapped it in bubble tape or hung it safely on the wall. But that would be no fun and besides I need something to eat my burrito bowls in. After all, beautiful things are made to be used and enjoyed!
So I will be googling how to repair broken dishes and making a note to self never to have granite countertops again.