Disaster!
Stupidly, to make it easier to file the 'head' of the sculpture I put it in a vice but closed up too tightly on the area of the stone with a flaw. I heard a worrying crunching noise and saw pieces of stone falling to floor. You can see the outcome below.
Funnily enough today I was going to use a mixture of stone dust and glue to fill in the crevice but instead I had to use it to stick back the stone chunks that fell out. Then I filled in the crevice.