Flint (or flintstone) is a hard, sedimentary cryptocrystalline silica rock with a glassy appearance. Flint is usually dark grey, blue, black, or deep brown in colour. It occurs chiefly as nodules and masses in chalks and limestones.
Along with chert, this mineral was one of the most commonly used materials for the manufacture of stone tools during the Stone Age, as it splits into thin, sharp splinters called flakes or blades (depending in the shape) when struck by another hard object (such as a hammerstone made of another material). It remained an essential mineral resource for making fire, including the flintlocks on early firearms, until the close of the 18th century.
In Europe, some of the best flint has come from Belgium (Obourg, flint mines of Spiennes ), the coastal chalks of the English Channel, the Paris Basin , the Sennonian deposits of Rügen and the Jurassic deposits of the Kraków-area in Poland. Flint mining is attested since the Palaeolithic, but became more common since the Neolithic (Michelsberg culture , Funnelbeaker culture).