The natural salt licks I've seen look like a plain open dirt spot void of vegetation. There's a depression formed from the deer eating it over many generations. It also may not be the salt, if there's any there, but some other mineral the deer crave or need.

I thought about hunting over/near one, but I've always seem to find better spots to hunt in that area. I usually see fresh tracks, several a week, but not enough to make me want to hunt over it.

I don't know if you've seen where a grouse or partridge likes to take a mud bath, but this too looks like a natural salt lick, only on a smaller scale. Natural salt/mineral licks have an aged looked to them from being there for many years. The ones I've seen all have a depression from all the deer digging and eating at them.

iSnipe