argillized

Argillized is a term used in geology and soil science to describe a rock or sediment that has been altered by the action of clay minerals, primarily through the process of argillic alteration. This alteration typically occurs when water rich in dissolved ions, often originating from hydrothermal fluids or weathering processes, interacts with pre-existing rock-forming minerals. The original minerals are broken down and their constituent elements are incorporated into new clay minerals such as kaolinite, illite, or smectite.

The process of argillic alteration can significantly change the physical and chemical properties of the affected material. It often leads to a decrease in grain size and an increase in porosity and permeability, although in some cases it can bind particles together. The color of argillized rock can also change, often becoming lighter or developing characteristic hues depending on the specific clay minerals formed and any associated mineral alterations. This process is commonly found in areas of hydrothermal activity, such as near mineral deposits and geothermal systems, and is also a significant aspect of soil formation through weathering. Understanding argillization is important in fields like mining exploration, geotechnical engineering, and soil science.