Clay tiles, commonly known as Qing tiles, are primarily made from clay (including materials like shale and coal gangue powder). They are produced through a process of mud treatment, shaping, drying, and firing. The color is not actually green but rather a dark blue or gray-blue. The production of Qing tiles in China predates that of bricks and they are mainly used for roofing, ridge tiles, and as tiles for eaves. Qing tiles offer a sense of simplicity, stability, rustic charm, and tranquility, making them popular in contemporary replicas of ancient architecture.