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I am trying to solve the mystery of making a fire with two stones.

I know that it is possible to make a spark with two quartzes thanks to the piezoelectric effect. But that is not enough to start a fire, I found out that some kind of metal is needed to start a fire. The quartz “peels off” the metal part and creates a metal spark, which thanks to oxidation and friction heats enough to start a fire. On the internet, I can find that using FeS2 (pyrite and marcasite) is possible. However, I cannot find why it is not possible to use just any stone with high metal concentration like hematite or limonite (is it because FeS2 is sulfide, while hematite is an oxide? If so, what role does it play?). It is also often mentioned that if you use steel and quartz, you should have high-carbon steel. What role does carbon play in it?

The other part of the question is if it is possible to find these stones in nature without too much digging or traveling to specific places. I can find quartz everywhere, but I have never seen pyrite or marcasite. And are there any stones which are very common and it is possible to use them?

I know it is a lot of questions, but if I get answer to at least some of them, I will be very glad.

Edit.: I live in the east of Czech Republic, central/eastern Europe, specifically Orlické hory if that helps.

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  • Wow, that is really cool :O Commented May 20 at 18:41
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    Burning generally means oxidation so oxide minerals aren't a good starting point. Even high carbon steel isn't very rich in carbon, but (if I remember rightly) its likely to be hard and brittle. That might make for better sparks. But fire starting with sparks usually uses cerium. Magnesium can also play a part. And you need very good tinder
    – Chris H
    Commented May 20 at 19:07
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    Thank you, it makes sense. So hematite and limonite (oxide minerals) cannot be used, because if I hit them the particle does not oxidate, so it cannot heat enough, while sulfides oxidate very fast. And the carbon part makes sense too :-) Commented May 20 at 19:32
  • Flints are not uncommon, but I think that people would carry one with them, rather than make camp and say "let's find a flint". Same with tinder: it would be gathered ahead of its need. I'll add that in the days of open fires in the home, we would prepare the kindling wood in advance, so that there was always a stock of dry kindling that would catch fire readily. Ditto when camping with open fires: ensure that you dry out some twigs ready for the next day's fire. Commented May 20 at 22:09
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    It is important to note that useful rocks, such as flint, were actually not a very common resource and were thus traded far and wide. There were flint trading networks back in the stone age spanning large parts of Europe exactly because A) flint was a very important resource and B) it was not easy to just find it locally in many places.
    – fgysin
    Commented May 22 at 9:25

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The main idea is, striking stones by itself doesn't produce enough energy to light a fire. You need something more substantial, like rubbing stuff together vigorously for some time, or one of your "stones" should be something that can burn.

In the latter case, when you hit your stuff, the following happens:

  1. At the point where the stones contact, potential energy accumulates in a form of stressed material. It is very concentrated, because the contract region is very small (a point).
  2. A small speck of material breaks off from one of the stones. As the material's stress is relieved, the potential energy is transferred into heat, which makes the small fragment hot enough to ignite at the point of breakage.
  3. The burning releases more energy, and the whole fragment starts burning. Up to now, a few milliseconds have passed; not enough to light any significant fire. However, with any luck, the fragment is big enough to sustain burning for a few seconds.
  4. If the burning fragment flies into tinder, it will produce enough heat to light it on fire.

Note that at several stages above some luck was needed, so you have to strike your stones several times (or be very experienced). And you absolutely need stuff which can (a) break and (b) burn. Steel and pyrite are some examples, but natural minerals like that are rare: if it could burn, why didn't it burn in a recent forest fire or during a recent lightning strike?


Why you need high-carbon steel: if you use steel, it should be hard and brittle, so small fragments of it could break off.

Why pyrite is OK but hematite is not: indeed, pyrite is a sulfide, which can be oxidized by the oxygen in the air. Most of the natural minerals (e.g. quartz) are already saturated with oxygen from billions of years of exposure to the air, so they can't take more oxygen.


If you want to start a fire, you better carry a suitable metal item to strike with a hard natural rock (like flint). Or, if you want to only use natural materials: nature has plenty of burnable stuff, so use e.g. the drill method with wood.

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  • Thank you very much, it answers all my questions :-) . Commented May 23 at 8:52

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