Bricks are made from clay. The clay is bonded by cement (mortar). The mixture is placed in a kiln and is subjected to up to 2,000° F during the firing process. The clay changes form as it dehydrates. The new anhydrous minerals contain interlocking (bonding) networks of mullite crystals, quartz, and some super-cooled liquid (glass). Brick has compressive strength, is durable, demonstrates thermal and sound insulation, is able to withstand severe weather, and is resistant to fire and wear.