Clay is a type of fine-grained natural soil material containing clay minerals [1] (hydrous aluminium phyllosilicates, e.g. kaolinite, Al 2 Si 2 O 5 (OH) 4). Most pure clay minerals are white or light-coloured, but natural clays show a variety of colours from impurities, such as a reddish or brownish colour from small amounts of iron oxide. [2][3]

Apr 10, 2025 · Clay, soil particles the diameters of which are less than 0.005 millimeter; also a rock that is composed essentially of clay particles. Rock in this sense includes soils, ceramic clays, clay shales, mudstones, glacial clays, and deep-sea clays.

Hexagonal sheets of the clay mineral kaolinite (SEM image, 1,340× magnification) Clay is a very fine-grained geologic material that develops plasticity when wet, but becomes hard, brittle and non–plastic upon drying or firing. [2][3][4] It is a very common material, [5] and is the oldest known ceramic. Prehistoric humans discovered the useful properties of clay and used it for making ...

clay mineral, any of a group of important hydrous aluminum silicates with a layer (sheetlike) structure and very small particle size. They may contain significant amounts of iron, alkali metals, or alkaline earths.

May 1, 2023 · Clay minerals are a group of minerals that are typically found in soils, sediments, and rocks. They are characterized by their small particle size, which is typically less than 2 micrometers, and their high surface area. Some of the most common clay minerals include kaolinite, smectite, illite, and chlorite.

Mar 21, 2024 · Claystone is a sedimentary rock composed primarily of clay-sized particles, which are minerals that are less than 0.004 millimeters in diameter. It belongs to the broader category of mudrocks, which also includes shale and siltstone.

Claystone, hardened clay. Some geologists further restrict the term to a sedimentary rock that is composed primarily of clay-sized particles (less than 1256 millimetre in diameter) and is not laminated or easily split into thin layers; such rocks that show cleavage roughly parallel to …

Jan 5, 2023 · The clay is a hard, tough, refractory clay consisting chiefly of the clay mineral kaolinite. Flint clay will not mix with water, and lacks the chief characteristic of clay: plasticity.

Mar 28, 2023 · Claystone is a clastic form of sedimentary rock. It primarily consists of tiny particles cemented into hard rock with a size of less than 1/256 mm. In terms of size, Claystone is comparable to siltstone and Mudstone. Therefore, Claystone’s formation …

The types of clay minerals found in weathering rocks strongly control how the weathered rock behaves under various climat-ic conditions (such as humid-tropical, dry-tropical, and temperate conditions).