According to geologists, clay comes from the decomposition of different rocks during geologic times.
Groups of clay
Clay can be part of different groups, based on its origin and properties. The Illite is a clay of marine origin and is extremely rich in minerals. The Kaolin group, taking its name from a Chinese province Kao-ling, is a gentle clay often used in facial beauty mask for its softness. The Smectite group, with its widely known Montmorillonite clay, is often referred to as French or green clay. Clay comes in many different colors: red, pink, yellow, brown, blue, white and green. Only the white and green clays are used internally. All the other colors of clay are used externally. Over time, clay undergo a natural process of transformation and can convert from one group to another. Therefore, clay found in nature is usually a mix of different clay groups, one group being dominant.
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