What were adobe bricks made of?

Traditional adobe bricks are made from local clay-rich soil, sand, water, and an organic binder. Straw is most common; dung, grass, animal hair, and wood ash were also used historically. The mix is shaped in a wooden mold and sun-cured for two to four weeks. Soil composition matters. New Mexico State University guidance specifies roughly 15–30 percent clay content for structural strength without cracking. The US Forest Service Adobe Architecture monograph notes that the practice dates to the eighth century BC. The same recipe appears across Mesopotamia, North Africa, and the Spanish-influenced Americas. The word adobe itself derives from the Arabic at-tūb via Spanish.