hydrotalcite

Hydrotalcite is a naturally occurring hydrated magnesium aluminum hydroxide carbonate mineral with the chemical formula Mg6Al2(CO3)(OH)16·4(H2O). It is a member of the hydrotalcite group of minerals, which also includes saponite and chamosite. Hydrotalcite is a layered double hydroxide with a brucite-like layer and an interlayer gallery containing carbonate and water molecules.

The mineral was first described in 1805 by Louis-Nicolas Vauquelin, who named it after the Greek word "hydro," meaning water, and "talc," referring to its similarity to talc. Hydrotalcite is typically found in sedimentary rocks and is often associated with other minerals such as dolomite and calcite.

Hydrotalcite has a wide range of applications due to its unique properties. It is used as a catalyst in various chemical reactions, particularly in the production of polymers and pharmaceuticals. In environmental science, hydrotalcite is used as a water treatment agent due to its ability to adsorb and remove heavy metals and other pollutants from water. Additionally, it is employed in the production of absorbents, animal feeds, and as a component in certain types of cement.

The crystal structure of hydrotalcite consists of brucite-like layers stacked in a hexagonal arrangement, with carbonate ions and water molecules occupying the interlayer spaces. This structure gives hydrotalcite its characteristic layered appearance and its ability to adsorb and exchange ions.

Hydrotalcite is generally found in the form of fine-grained, white to grayish-white, or yellowish-white crystals. It has a hardness of approximately 2.5 to 3 on the Mohs scale and a specific gravity of about 2.5 to 2.7. The mineral is non-fluorescent and has a vitreous to pearly luster.