Yes mineral sites effective. I have one at a couple of sites that I bow hunt. The mineral that I use I get from TSC and it is high In calcium and then I put out the trace mineral salt ( red & loose with out medication) and a bag of rock salt. I also put out rice bran.

I agree mineral licks do benifit the deer,especially when fawns are born and durning antler development.Around here,the deer don't seem to vist them much during our hunting season.