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Clay clay is generally formed by weathering of silicate minerals on the Earth's surface. Generally in situ weathered, larger particles and close to the original stone, known as the primary clay or clay. The main component of this clay is silica and alumina, white and fire-resistant, the preparation of clay for the main raw material.

Clay machine and clay will continue to weather and become younger, and then by water and wind migration, and in the downstream to form a thick layer of clay, called secondary or secondary clay. This clay is contaminated with more metal oxides, darker colors and lower refractoriness. Due to good viscosity and plasticity, the main raw material for the preparation of clay.

Kaolin kaolin clay kaolin is the main component of the soft clay. Mainly composed of kaolinite minerals. In nature, the minerals that make up kaolins are clay minerals and non-clay minerals. The color is white, the highest whiteness is more than 95%, the hardness is 1 ~ 4.