# Opal Mining Town in Australia #

Vaporizing the rock:No Need for that.
We only need to drill upward at about a one or two degree incline to allow melted rock to flow out of the tunnel. Start the tunnel a few meters above the ground and the melt would make a nice ramp to the entry, plus the slight incline of the tunnel would allow for construction of a false floor to provide for underfloor cable troughs, water piping and sewage lines, all necessary adjuncts for a long term living facility.
I try to go for the cheapest, simplest tech in such an endeavor, which is why I proposed the flat mirror heat source. I expect highly reflective Mylar, stretched over a light weight frame, could be shipped rolled up, like the old movie pull down screens we used to use for 8 mm film home projection screens in the '60s/'70s. Telescope clock driven mounts would allow the mirrors to accurately track the sun, maintaining their focus on the desired spot.