Flint is a microcrystalline variety of quartz. Materials of this description have been given a wide variety of names, including chert, jasper, agate, and chalcedony. Most geologists use the word “chert” instead of “flint”.

Some people believe that the name “flint” should be reserved for dark-colored chert that formed as nodules in limestone or chalk. Some archaeologists believe that the name “flint” should only be used when the material has been fashioned into an artifact.

The name “flint” has been so closely associated with starting fires that man-made materials used to produce sparks in cigarette lighters and survival kits have been given the name “flints.”

“Novaculite” is a metamorphic rock that is similar to flint. It has a sedimentary origin, just like flint, but diagenesis and metamorphism have increased the size of the quartz microcrystals. It has been used for thousands of years for making sharp tools and weapons. Some specimens have a texture that make them useful as a sharpening stone.