Help with maple burl. Archive

I have a maple burl that is about 5 feet long and 2 1/2 feet wide and about 3 inches thick. I leveled it out about 4 years ago and put a clear epoxy in the cracks (not too many) and voids. it has been sitting on edge for the last 3 or 4 years. I have two problems, 1) is that there is a light blue powder on the surface, it wipes off easily. What is the best way to take care of this, is it safe as far as breathing it goes? and 2) any ideas of what to make out of this? I will post some photos if anyone is interested. Thanks for any help and ideas anyone can give me.