Flint and chert are the most commonly knapped materials and are compact cryptocrystalline quartz. The difference between the two terms is colloquial, and flint can be seen as a variety of chert. In common usage, flint may refer more often to high quality material from chalky matrix (i.e. "chalk flint" as found in Britain) and chert refers to material from limestone matrices. To avoid this, the term "silicate" may be used to describe the family of cryptocrystalline quartzes that are suitable for knapping. As well as cryptocrystalline quartz, macrocrystalline quartz (both vein quartz and rock crystal) was a commonly used raw material around the globe.