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How to avoid exploding rocks

If I build a campfire with damp rocks, is there any possibility of the rocks exploding? I had this happen once while burning trash, because the moisture in the rock swells as it heats and the rock pops like popcorn. Is there any chance that this might happen if I use damp rocks to line and/or floor a campfire?


1 Answer 1


Rocks wet or dry can violently fracture if exposed to enough heat due to cavities.

The type of rock may actually have more to due with possible explosions than the moisture level. Meaning igneous and metamorphic are non permeable, but can contain natural oil or flint which can be bad. Sedimentary limestone, shale, sandstone would have a better chance of explosion due to water, but see below.

The best answer to your question would be, use soil not rocks.

And, normally a low impact campfire should not have the heat needed.

  • What should I do if the ground is frozen? It often freezes two feet down here.
    – J. Musser
    Commented May 3, 2012 at 1:23
  • The odds of having a violent rupture are extremely low. Having frozen earth should actually reduce the chance of a rupture because the ice will require more heat over a longer period of time to get to the required pressure. In other words it is kind of a non issue. Just don't throw river rocks in really hot fires, or use shale that is naturally brittle. Commented May 3, 2012 at 1:37

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