Flint is a hard, sedimentary cryptocrystalline form of quartz that has been historically and industrially significant for millennia. Its most famous historical use was as a tool for creating fire; when struck against steel or another hard stone, it produces sparks that can ignite tinder, a method used globally until the invention of modern friction matches. Beyond its historical role, flint has been used to create sharp cutting tools, arrowheads, and blades, as it breaks with a conchoidal (shell-like) fracture that results in extremely sharp edges. In the modern era, flint is used as a high-quality building material, particularly in historical architecture, and in the production of specialized ceramics and porcelain, where it is ground down to act as a silica source. Its hardness and durability also make it useful in certain abrasive applications, continuing a legacy of utility that spans from the Stone Age to contemporary industrial and decorative masonry uses.