Until recently flint was also an important raw material in clay-based ceramic bodies produced in the UK.[18][19] In preparation for use flint pebbles, frequently sourced from the coasts of South-East England or Western France, were calcined to around 1,000 °C (1,800 °F). This heating process both removed organic impurities and induced certain physical reactions, including converting some of the silica to cristobalite. After calcination the flint pebbles were milled to a fine particle size.[20][21][22][23] However, the use of flint has now been superseded by quartz.[24] Because of the historical use of flint, the word "flint" is used by some potters, especially in the US, to refer to siliceous materials that are not flint.[25][26][27]