When Bear Grylls dashes off into the wilderness to film the survival show Man vs. Wild , he is often prepared to make fire with a rather fascinating metal alloy.

At the beginning of nearly every episode, the famous adventurer explains that he is equipped with "only a knife, a flint, and a water bottle." However, his handy firestarter is not a piece of rock. It’s a rod made from a blend of rare earth elements called mischmetal — which is mostly cerium.

When scraped with a knife, tiny particles fly off of the metal bar. As their freshly exposed surfaces come in contact with air, the little bits of metal oxidize — becoming super hot sparks.

Safe and sane flash bang grenades, developed at Sandia National Laboratories, operate under the same general principle. Hurl a cloud of tiny un-oxidized metal particles into the air. Bang! They will violently react with oxygen.

On the other hand, the old-fashioned way to make a fire is more challenging, but it operates on the same principle. The sharp edge of a flint stone can scrape tiny specks from a high-carbon steel bar. As they come in contact with oxygen, the bits of metal ignite.

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