Main components are natural raw materials  

Bricks are mostly made from clay and shale – some of the most abundant, natural materials on earth – and then fired through a kiln at up to 1,000 degrees. Brick is such a durable material because the raw materials go through a vitrification process in the kiln, which enable the material particles to fuse together. Clay and shale are also found in most areas of the world, meaning that the materials can usually be sourced locally, thus minimising the distance travelled between raw materials and production.