The mineshaft itself houses miners at the top floor, whilst heavy machinery such as drilling machines lurk at the very bottom of the mine. The very bottom of the mine houses large quantities of gemstones - some large enough that machinery is required to pull them up to the surface. However, there is a downside to the digging as the miners have almost penetrated the outer crust of the planet, so it gets extremely hot down in the depths of the icy ground.