claymineralit

Claymineralit are hydrous aluminum silicate minerals with a layered phyllosilicate structure that form a major fraction of fine-grained clays in soils and sediments. Their fundamental framework consists of silicate tetrahedra linked to octahedrally coordinated metal cations (usually aluminum and magnesium), arranged in sheets. These sheets stack to form 1:1 (one tetrahedral sheet with one octahedral sheet) or 2:1 (two tetrahedral sheets sandwiching one octahedral sheet) structures. The substitutions of ions in the sheets generate permanent negative charges, which give claymineralit high surface areas, variable cation exchange capacity (CEC), and distinctive swelling and plastic properties.

Common claymineralit are categorized as 1:1 clays such as kaolinite and halloysite, which have low CEC and minimal interlayer water; and 2:1 clays such as smectites (montmorillonite), illite, and chlorite, which show greater cation exchange capacity and in some cases swelling. Vermiculite is often described as a 2:1 clay with expandable layers but different substitution patterns. In addition, non-crystalline or poorly crystalline clays (e.g., allophane, imogolite) are sometimes included in broader clay mineral studies.

Formation occurs primarily by weathering of primary silicate minerals (feldspars, micas) under varying temperature, humidity, and chemical conditions, as well as diagenetic and low-temperature hydrothermal processes. They are abundant in soils, sedimentary rocks, and claystones, and influence nutrient retention, soil structure, and contaminant sorption.

Applications and analysis: Claymineralit play key roles in agriculture, ceramics, drilling fluids, environmental remediation, and waste containment due to their sorption properties and plasticity. Identification and quantification rely on X-ray diffraction, electron microscopy, and spectroscopic methods, often complemented by CEC and surface-area measurements.