I haven't used mineral blocks in years and couldn't remember how long they would normally stay on the ground but I put out three in late March and the one in these photos has gone into the ground. The other two that I put out you can barely tell that they are used except where the water runs off the top of them.
I feel like the one shown here has had more activity because I had already been putting salt in this hole for the last couple of years so they were kind of used to this spot but I didn't think that it would dissolve this fast. Anyway, it sure seems to be getting some attention! LOL