A good friend of mine informed me the other day that they were working on a new Challenge requiring a find of a multi-cache in 64 different Texas counties (GC9DBA5). And that there were currently NO ACTIVE Multi's in all of Lee county. Followed by "Could I help?", he asked politely. Well you know me, of course I can! Any excuse to hide a new cache is a great idea.
So, here is the new multi-cache.
At the posted coordinates you will see a sign for the Three Oaks Mine giving its Federal MSHA (Mine Safety and Health Administration) I.D. Number. Since that is easy to look up, what you need to obtain is the Texas Railroad Commission Permit Number - nnnX. I'm sure that can be looked up too, but whatever.
To calculate the final coordinates, convert the letter 'X' to a number using A=1, B=2, etc. Multiply 'X' by the two digit number in 'nnn' and add that to the posted north coordinates. Then subtract 37. That is your final north coordinates.
Then take the second digit of 'nnn' followed by the first digit of 'nnn' to create a two-digit number. Subtract that value from the posted west coordinates. That is your final west coordinates
Good luck, but it should be an easy find.