Finally got a clean break on that stubborn basalt sample from Mount Rainier

I've been trying to get a good thin section from this dense piece for weeks, but it kept shattering. My professor mentioned trying a cold chisel after heating the rock just a bit with a propane torch for 30 seconds. I gave it a shot yesterday, focusing the heat on a single line. The rock split right along the plane I wanted, leaving a perfect face for polishing. Has anyone else had luck with thermal shocking on really tough igneous rocks?

3 comments

3 Comments

julia923mo ago

Ugh, that sounds like a great way to wreck your sample and your tools. Heating it even a little can totally change the mineral structure... you might have just created micro-fractures you can't even see yet. A proper rock saw with a diamond blade is slow but it's the only way to get a true, unaltered surface. You're basically cooking the rock before you even look at it.

julia6223mo ago

Wait, they're heating the rock? That's insane. You can't just bake a sample and expect to see anything real.

alice_harris352mo ago

Totally, heating it is asking for trouble (even a little). I tried something like that on a granite sample once and the whole internal structure just went cloudy under the scope. You're better off just being patient with the saw, honestly.