Molten Core is the 5th layer of The Overworld mine in Mining Simulator 2. This layer of the mine begins when you reach a depth of 1,117. The layer continues until a depth of 1,476.
The Molten Core lobby is where you can access the second shop in the game. Next, head over to the Lava Fiend standing by some black rocks to check out the new gear available here.
There is no free chest to claim in this layer, but there is an egg that you can hatch while there (Volcanic Egg).