If I came across this in my hive I would have to say it is winter stores that has granulated and the bees are now removing it to allow extra room for the queen to lay. In UK it could come from Ivy as this would granulate over the winter period.
With Chalkbrood you should see small mummiefied larva on the floor or collecting tray. The colour will bee white to dark grey to black. Also the larva in the cells would be covered in a fungus which in turn kills the larva, I must addmit it does not look like Chalkbrrod.
A description of the contents would help decide what it is.