Clay mineralogy is the branch of mineralogy that focuses on the study of clay minerals, which are hydrous aluminum phyllosilicates and are commonly found in sedimentary rocks and soils. Clay minerals are important in a variety of scientific fields, including geology, soil science, and ceramic engineering. Researchers in clay mineralogy study the physical and chemical properties of clay minerals, their formation processes, their interactions with other minerals and compounds, and their role in various geological processes such as weathering, sedimentation, and diagenesis. The study of clay mineralogy can provide insights into the Earth's history, environmental processes, and the development of natural resources.