Well, after using a bunch of bags of hard rock sugar, I'm here to report my findings.
No matter what, you have to use 'some' brute force to break up a 5 lb bag (and I found I HAD 7 of those in the pantry!) A hammer or a knife will break it up into chunks.
Tested the following methods:
The food processor did a good job of breaking up the rest just don't process it into a fine powder.
The microwave on high power for 15 seconds softened it enough so I could mash it between my fingers to a fine granule.
There was no off taste from the humified sugar and it works well in canning and in baking.
Hope that helps anyone that has some rock hard sugar. ~Blissful