if high-pressure water jets can cut steel, they can surely cut through rock; so no cutting teeth to wear out. the jets would be in a cross-hatched pattern to reduce the cuttings to an easily pumped slurry. the jets could also have ultrasonic transducers for really hard-going stuff, computer-tuned to the appropriate frequency to shatter the rock (just like kidney stones)-- philmckraken, Jun 07 2004 i'm not just talking about mining, but a cheaper more economical way to make road or rail tunnels...with a big tunnelling machine (the machine could also create the tunnel walls as it goes by fusing the rock at high temperatures into artificial obsidian. but that's getting really half-baked)-- philmckraken, Jun 07 2004 See the book "Novel Drilling Techniques" or perhaps it is "Novel Drilling Methods". I forget which. The second edition gives cutting rates of several meters PER SECOND. No explosives required.-- Kirkmcloren, Aug 14 2006 random, halfbakery