"I shall first treat of bricks, and the earth of which they ought to be made. Gravelly, pebbly, and sandy clay are unfit for that purpose; for if made of either of these sorts of earth, they are not only too ponderous, but walls built of them, when exposed to the rain, molder away, and are soon decomposed … They should be made of earth of a red or white chalky, or a strong sandy nature. These sorts of earth are ductile and cohesive, and not being heavy, bricks made of them are more easily handled in carrying up the work."
Marcus Vitruvius Pollio, De Architectura, Book II, Chapter 3
Bricks are an ancient building material, and are most commonly made of clay and water. Originally they were baked by the sun. They are blocks, usually small ...