1, Tai Chi soil, also known as five-color soil, Tai Chi halo, in geomantic omen, the popular school thinks that it refers to the dragon cave, that is, at the junction of a dragon cave, there must be five circles of different colors wrapped around the sun, and each layer is a color, with different shades and shades.
2. Pottery clay is a kind of clay used to make pottery, which refers to iron-containing clay, which is yellow-brown, gray-white, red-purple and other colors, and has good plasticity. The mineral components are mainly montmorillonite and kaolin. Pottery clay is mainly used for firing exterior walls, floor tiles, pottery utensils, etc.