Two specific geological materials—Iron Pyrites (left) and Flint (right) found in the ash layers of ancient cave floors 插畫檔

This image illustrates one of humanity's earliest and most vital technological breakthroughs: the ability to create fire on demand.The Iron Pyrite (The Fuel): Often called "Fool's Gold," this mineral is an iron sulfide (). When struck by a harder object like flint, tiny particles of the pyrite are shaved off. These particles react instantly with the oxygen in the air (a process called oxidation), which generates enough heat to create a "hot" spark.The Flint (The Striker): Flint is an incredibly hard, sedimentary cryptocrystalline form of the mineral quartz. Its hardness and sharp edges make it the perfect tool to strike the pyrite and "shear" off those combustible particles.