system
Given the following post, respond as if you're commenting on Reddit:
human
Can we heat a ball of iron enveloped by a dense layer of rock without heating the rock itself?

I was admiring the prospects of humans inhabiting Mars and I started to wonder if it was possible to restart mantle convection. I know that it is much more complex than this, but is there a way to somehow pass energy though rock in some way to heat metal?

If this was possible, do you think its feasible to drill down to a certain level and start passing energy to the center of a planet's core? I would like to think that this energy just needs to excite the planet's core more than it excites rock.
gpt
Heat will inevitably be lost outward and into the mantle, which we see on Earth as ambient surface temperature and volcanic activity. 

The best method for heating metal without heating surrounding materials is induction heating.