What Are Clay Minerals?

Clay minerals refer to hydrous aluminosilicate minerals with a layered structure and are the main mineral components that make up clay rocks and soils, such as kaolinite, montmorillonite, illite, etc.

Clay minerals are the most important mineral component of clay rocks. The most common clay minerals are layered structural silicate minerals, mainly kaolinite, kaolinite, montmorillonite, hydromica, chlorite, chlorite and so on. Amorphous clay minerals include gibbsite and chain-shaped structures such as sepiolite. The chemical composition of clay minerals is mainly SiO ₂ , Al ₂ O ₃ and water, and the composition of each mineral is different. For example, kaolinite has the highest Al ₂ O _{3 content} , sepiolite has high MgO content, and water mica content. K ₂ O is the most. Different clay minerals have different crystal structures, shapes, and physical properties, which can be used as the basis for identification. Clay minerals have the ability to adsorb ions from the surrounding medium. This affects the properties of clay rocks on the one hand, and on the other hand, valuable mineral deposits are formed when certain useful elements are absorbed. ^[1]

Clay minerals are important factors influencing sandstone reservoir performance. The genesis, absolute content, composition, occurrence, and crystal morphology of clay minerals are all related to sandstone storage performance. Studies have shown that the degree of influence of clay minerals on sandstone storage performance is related to the maturity of the sandstone itself. When sandstone maturity is high, as the absolute content of clay minerals increases, its storage performance decreases, especially its permeability. However, high maturity sandstones increase with kaolinite and filling clay mineral content, and their physical properties become better. When the structure and composition maturity of sandstone is relatively low, clay minerals have less influence on its storage properties, and are mainly related to the composition and structure of the rock itself. The study also shows that different forms of illite have different effects on the physical properties of sandstone. Flaky illite is beneficial to improve the physical properties of the reservoir, while the increase in fibrous and hairline illite will reduce the physical properties of the sandstone reservoir or become non-reservoir Floor. ^[2]

Clay minerals can change during sedimentation and burial. Its formation and transformation are closely related to the environment in which it is located. Therefore, in-depth studies of the changes and combinations of clay minerals, their structural characteristics and transformation laws, and their particle size distribution characteristics can be inferred from the types of weathering in their formation and source regions. The law of climate evolution helps to reveal the law of global environmental evolution. Information on the evolution of the paleoclimatic environment revealed by a large number of studies on clay minerals has been used to reconstruct the paleoclimate and restore the continental paleoenvironment. In addition, because clay minerals have strong adsorption, ion exchange, and swelling properties, they have good adsorption properties for various types of pollutants in water and make the soil have a certain self-cleaning effect. Therefore, it is useful in the prevention and control of environmental pollution. Has broad application prospects. ^[1]