used in the construction
. In early brick firing kilns, the surface of the bricks that were too close to the fire changed into the volcanic textures and darker/purplish colors, and were called "clinkers". They were originally discarded, but around 1900, these bricks were discovered by architects
to be usable, distinctive and charming in architectural detailing, adding the earthy quality favored by Arts & Crafts style designers. Modern brick-making techniques can recreate the appearance of these bricks and produce a more consistent product.
In the United States, clinker bricks were made famous by the Pasadena, California architecture firm Greene and Greene who used them (often in combination with native rocks) in walls, foundations, and chimneys.
The name "clinker brick" is said to come from the sound that they would make when banged together, being heavier than regular bricks; however, this term is also used for the hardened residue of coal fires, that can have a similar texture.