My reading in various places is that it is better to offer loose, broken salt than a licking block, for obvious efficiency reasons to the animal. Here, I buy 50lb "bricks" (appx 10"x10"x26") of salt as it mined from the ground. It is actually quite hard to break even into somewhat smaller pieces, usually making a mess as bits go flying in all directions.
I've solved recently the getting from one huge block to about 10-20 smaller bits by drilling a hole with a hammer drill and using two grams of blackpowder to fracture it. By exploding in a
feed sack, the pieces are kept in one place, so I don't lose any salt. But I still have large hunks that I want into sort of rock-salt like granules. I guess I could just beat the feed sack with a hammer for awhile, but isn't there some more elegant way to do it?