smectite
Quick Summary
Smectite is a group of clay minerals known for their ability to swell in water and their high cation-exchange capacities. These minerals are primarily composed of hydrous aluminum silicates and are characterized by their 2:1 silicate layers, which have a slight negative charge due to ionic substitutions. This negative charge is balanced by interlayer cations.12
A key feature of smectites is their capacity to absorb water and other polar molecules between their unit layers, causing the structure to expand. This property makes them valuable in various industrial applications, including as bleaching earths for purification, catalyst supports in petroleum refining, and as the main components of bentonite and fuller's earth. Smectitic clays, particularly bentonite, are crucial in drilling muds for oil wells due to their swelling and colloidal properties. They also play a role in environmental science, serving as barriers for radioactive waste and absorbing pollutants.213
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clay mineralSmectiteThe structural units of smectite can be derived from the structures of pyrophyllite and talc. Unlike pyrophyllite and talc, the 2:1 silicate layers of smectite have a slight negative charge owing to ionic substitutions in the octahedral and tetrahedral sheets. The net charge deficiency…
Read MoreThe structural units of smectite can be derived from the structures of pyrophyllite and talc. Unlike pyrophyllite and talc, the 2:1 silicate layers of smectite have a slight negative charge owing to ionic substitutions in the octahedral and tetrahedral sheets. The net charge deficiency…
Read More- clay mineralSize and shape
Electron micrographs of smectite often show broad undulating mosaic sheets. In some cases the flake-shaped units are discernible, but frequently they are too small or too thin to be seen individually without special attention.
Read MoreElectron micrographs of smectite often show broad undulating mosaic sheets. In some cases the flake-shaped units are discernible, but frequently they are too small or too thin to be seen individually without special attention.
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