Going on a tangent, minecraft might have taught most of us that we can spark fires simply with a flint and a steel, but it is also possible with just two types of rocks, albeit with less efficiency. With flint and steel, what happens is that using the flint (or any rock in the flint family which includes quartz, agate, carnelian or even obsidian, the main criterion is the high silica content and harder than the steel) to strike the steel chips away pieces of it, and it is the friction that heats up the pieces hot for a while enough to ignite the dry material underneath.
The other method, replaces steel with rocks that are high in iron content. The science is the same, it doesn’t spark as easily but is much more naturally occurring than steel.
Another third method, actually involves replacing steel with iron pyrite, and this is interesting because the science is a bit different. By using the flint to chip away at the iron pyrite, the parts and pieces of the iron pyrite that are inside and not exposed to the air immediately reacts with the oxygen and ignites on its own.