Small blue tiles made of clay.

Small blue tiles made of clay are also called yin-yang tiles in the north and butterfly tiles in the south. Yin-Yang tile, commonly known as cloth tile, is an arc tile. Hand-shaped, there is another process after cooking, that is, baking, and the chemical reaction after baking is blue-gray. Maximum specifications range from 30×24, 24×20 and 20× 18. It is an advanced ancient building material for building towers, palaces, pavilions and various garden buildings. It is mostly used for township houses, but not for important buildings in big cities.

Taking cultivated land as raw material, it is fired in a kiln. Rough surface, slow water flow, high water absorption, low price and easy construction.

Small blue tile roof is heavy and easy to break, not as good as clay flat tile.

The consumption of small blue tiles is decreasing year by year. In areas with high population density and little arable land, the use of small blue tiles has been banned.