WW:
Hmmm. Do you all have some "secret formula" passed down from generation to generation or will just about any trace mineral do? If you have one, I'd sure like to get it. You are probably right as usual, as I don't know of any licks anywhere near where I hunt. I've seen several natural licks down in Kentucky, but none in Indiana.
JONB:
Over here we usually just buy some of the 10 kg salt stones that are used for cattle etc., put up a pole, thread the stone ontop (at about 1m height), and over it with a "lid" of some sort (or it'll rain away reasonably quick)
Some water will still wear on the stone, and cause some salt to run down along the pole, making it available to other animals other than deer.
I set up one some years ago, and two weeks later, the dry grass covered
ground around the pole was turned into a swamp 10x10 metres wide... ;)
BS:
we used to use oyster shell, phosphate rock, potash feldspar, block sulphur, ... but now we use mill blends, like everybody else, i suppose.
i suspect about any salt & mineral mix will do, but i'd get plenty of additional trace elements added, too, and the more the better. about any fertilizer mill can do it. what you need to do is plow or disk it in - deep and concentrated. and a lot of it. we disc it in 6" at a time, and then top dress it a couple of inches, then water it in.
WW:
I've got to be careful with any salt as it is a consumable and the DNR... He'd like to catch me a 1/4 mile away from a lick and then swear that I was on a run that led to it.
BS:
have the mill make you up a fine grind, because you want it melted into a component of the dirt as soon as you can, because deer don't eat salt, but they do eat salty dirt. unless the warden wants to run a soil analysis, all he's going to know is that you are hunting over one hell of a nice size scrape.
remember, if a little does a little good, a lot does a lot of good.