With CWD creeping in, I'm thinking about abandoning our salt licks. For the last 20 years, I've used 1 bag of trace mineral in march and then 1/2 a bag replenishing those licks around the end of June.
This is what I've been doing for years. It's a firewood chunk cut flush on bottom and bowled out on top. I use a 1" boring bit to drill a bunch of 3-4" deep holes all over the top. Between being bowled out and porous from the holes, it holds a lot of the mineral. By hold I mean the mineral & salt permeates the wood little by little over time. My two oldest ones are almost like concrete now. They must weigh more than 50lbs, way heavier than they ever were naturally. It does quite well at keeping the deer's faces off of the ground. They'll lick all over the sides and top but not often do I catch them licking the dirt.
I fill the holes and bowl with the salt/dical/min mix then lay a Trophy Rock on top.
Pic on left kinda shows a clear-ish pic of the pedestal. I'll take a closer pic of the top if you'd like. The middle pic shows how they use it. The last pic also shows how they use it but it's a different, generally much busier site with two pedestals. TSC was out of rocks so I subbed it with a white salt block. Notice the deer lick the wood, not the actual rocks or blocks. I assume it's because the wood is already saturated with mineral & salt. They continue doing that even if I haven't refreshed the site & no mineral is visible.
I have no idea if this is any safer for the deer than licking dirt, but I would have to think so. If nothing else it makes me feel better and makes for cool pictures.