Guanyin soil was once used as food by hungry people during the three-year famine, and it temporarily relieved hunger.

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Guanyin soil is also called kaolin, also known as swelling rock, bentonite, sweet soil, bentonite, clay and white mud.

Guanyin soil is rich in minerals such as silicon, zinc, magnesium and aluminum. It is a clay mineral, and its chemical composition is quite stable, so it is known as "universal stone".

Baidu encyclopedia, Guanyin soil.