Why have we not drilled or mined deeper into earth?

Easy its too hot.

The deepest man made hole is Kola Superdeep Borehole. That was a Russian experiment to see how deep you could drill into earths crust, reaching down 12,262 meters. At that depth the temperature reached 180 °C. The scientists estimated that a 15,000 meters depth the temperature would reach 300 °C, and at that temperature the drill would cease to work and the project was stopped.

b) the inside picture would look at a very high temperature in a very low ph