“12/ Moving On (Mine Depletion) « Back To Top
Mining can affect the land, damaging it. When a mine is depleted there is a 33% risk that the land is damaged and is transformed in either grass, rock, crater, or desert. ”

Does this mean the slab might transform into one of these terrain types?

no

We have had instances where this has happened so the answer is yes. Does seem weird seeing a desert mid a load of glaciers but we have had it.

See Okyaab 3 planet at 0,0. The top row used to be all glaciers along with the bottom row but now we have a desert too. Global warming FTW!

the slab does not transform ...
the terrain beneath, yes. the slab, no.