This is a unique bug.

In Sector 1 there are 2 marble fields. A Northern and a Southern deposit (based on position of the two marbles I will be talking about the Northern deposit).

If you have nothing at the spot that can become the marble deposit (nothing there no deposit and no exhausted mine) there is a possibility to transfer a garrison to that spot. If you do and then a marble deposit is discovered later, the two will occupy the same space (garrison and Marble deposit). When the deposit is all mined out the garrison will disappear and the exhausted mine will stay. The garrison will still be responsive (read: the pop-up for the garrison shows up).

I haven't tested to see if there are any issues accessing this "destroyed" garrison. But I have found this also works for any other building placed in that spot. I first found this with a lvl 1 NR (Deeded version thankfully) that when destroyed went back into my starmenu.

1. Northern marble in S1 empty
2. Place garrison (or other building) in the spot
3. Discover marble in Northern spot
4. Exhaust marble in Northern spot & lose building
5. ...
6. profit (sorry I couldn't resist)