Here is a recipe that is very close to a formula I have used in " mineral pits" for sometime with very good results. I have witnessed that deer have eventually established feeding routes (patterns) that take them through the " pit" areas from spring through the first (approx) two weeks in October.

I formulated my recipe after having a discussion with a deer biologist I met in the field several years ago. The small difference in the recipe in the following link and my recipe is that I use a cattle block to obtain the Dicalcium Phosphate and Trace Mineral Salt, and granulate the block and ice cream salt together with a 60-year old Hobart commercial coffee grinder.

HOWEVER, if you are not familiar with cattle blocks, or do not want to take the time to research all the scientific names of all the minerals in a certain type of block, I strongly suggest that you use the posted recipe (link). Some cattle blocks contain Urea, particular protein sources, and fluorides that could be very bad for deer...or cattle, if too much is consumed per day.

This posted recipe appears to be very specific and safe.

http://walden.mvp.net/~gam/Mineral%20Page.htm