Mining fire by sparking is one of the oldest ways to get fire. Sparks are carved with flint or quartzite and a chair (flint). As for the stone, there are several opinions.
The production of fire by carving sparks, a flint from a pencil and flint for lighters.
Some argue that the stronger the stone, the better, and are supporters of quartzite. Relatively pure silica with a polycrystalline structure. Others believe flint gives more sparks. Silicon oxide having a cryptocrystalline structure with a large number of inclusions. The general recommendations are that the stone should be massive enough, and the blow should be strong enough and directed along the tangent from top to bottom in the end face of the chair. The direction of impact is of great importance..
A large piece of hardened iron is used as a chair so as not to injure your fingers. Flint can be in principle any form. So, previously used pieces of iron in the form of buckles, arches and so on. An interesting version of the flint was in the form of a tube, inside which a tinder or piece of burnt rope was put, and flinted along the edge. Before the invention of iron, some types of iron ores (pyrites, pyrite) were used as flint..
Flint from a pencil and flint for lighters.
Now some companies like to supply industrially assembled survival kits with an impromptu flint obtained by pasting pieces of flint for lighters into a pencil. It is possible to independently make such a flint as follows. The pencil is glued, for this it needs to be slightly warmed up, because it is glued with thermoplastic glue. A slate rod is removed from it and instead of it pieces of flint for lighter are placed on the glue. The pencil sticks together again.
Now, if you carefully grind it and strike it on the hard, rough surface of the flint, then a sheaf of sparks will fly out. The standard flint for lighters is an alloy of the following composition: cerium 66%; lanthanum 8%; iron 25%, magnesium 0.5%; copper 0, 5%. Sparks from flint and armchairs can ignite pieces of dry (especially gray, unrefined) cotton wool, dry chopped moss, bird fluff, finely chopped tree bark, dust from insect-eaten trunk, willow core, and so on, but it’s more convenient to use your own made.