Adobe bricks, fired from clay, which is a product of long-term weathering of certain aluminum silicate minerals and is named for its粘性. After the clay is mixed with water to form brick molds, it is fired in a kiln (at about 1000℃) to become bricks. Iron is present in the clay; when fully oxidized during firing, it produces ferric oxide, giving the bricks a red color, commonly known as red bricks. However, if water is added to cool the bricks during firing, the iron in the clay does not fully oxidize, resulting in ferrous oxide (FeO), which gives the bricks a blue color, known as blue bricks. The hardness of blue bricks is similar to that of red bricks, but they differ in the cooling method after firing. Red bricks are allowed to cool naturally, which is simpler, and thus, more red bricks are produced. Blue bricks are water-cooled (an oxygen-deprived cooling method), which is more complicated to handle, and thus, less are produced. Although their strength and hardness are similar, blue bricks exhibit superior properties in terms of oxidation resistance, hydration, and atmospheric erosion compared to red bricks.