Four days later, after awakening from his slumber in the mysterious mine, Jacob stepped out from the tunnel hidden within the poison mist.
As for why it took him four more days to exit the place, it was, of course, because he was extracting the plutonium from the other side of the mine. He naturally won't leave without that plutonium since he was here for it in the first place.
Although the amount of plutonium wasn't as much as he was expecting it to be, but it wasn't small either. He got around over 3 tons of it, and Jacob knew it was enough to last him for a long time, and he would be able to create many of his deadly inventions.
The biggest gain in this entire trip was naturally the Cursed Path Glory Gem as well as the Mysterious Book, and plutonium seemed nothing but dust in front of those two things.