Materials used in making bricks
The main materials used in the manufacture of bricks are:
Clay An alluvial deposit found in lowland areas. There are three main types:
Calcium silicate These bricks are made from a mix of hydrated lime and water and silica sand (or crushed flint), which is pressed into shape and then pressure-steam baked in an autoclave to produce a dull, white, and very regular brick. In 1877, the German chemist Dr Wilhelm Michaëlis first produced "artificial sandstone" ...