Leirestoffer

Leirestoffer, often translated as clay minerals, are a group of hydrous aluminum phyllosilicate minerals. They are typically formed by the slow chemical weathering of pre-existing rocks over geological timescales. These minerals are characterized by their fine grain size, often less than 2 micrometers, and their platy or fibrous structure. The layered structure of clay minerals allows them to absorb and release water, which contributes to their plasticity when wet and their hardness when dry. This property is fundamental to their use in various industries.

The primary components of most clay minerals are silica tetrahedrons and alumina octahedrons, arranged in distinct layers. Variations in the stacking and bonding of these layers, as well as the presence of interlayer cations like sodium, potassium, and calcium, lead to the formation of different clay mineral groups, such as kaolinite, illite, and smectite. Each group possesses unique physical and chemical properties that dictate their applications.

Leirestoffer are ubiquitous in Earth's crust and play a significant role in soil formation, water purification, and geological processes like sediment transport and diagenesis. Industrially, they are essential raw materials for ceramics, bricks, tiles, paper manufacturing, cosmetics, and pharmaceuticals. Their ability to adsorb ions also makes them valuable in environmental remediation and as catalysts.