overtonit

Overtonite is a rare mineral composed primarily of titanium and niobium. Its chemical formula is often represented as (Ti,Nb)O2, though variations can exist with other trace elements. It is a member of the rutile group of minerals, characterized by its tetragonal crystal structure. Overtonite typically appears as opaque, black to dark brown crystals. It is known for its high refractive index and can exhibit a submetallic to metallic luster.

This mineral is found in specific geological environments, usually associated with alkaline igneous rocks and carbonatites. It forms under conditions of high temperature and pressure. Notable occurrences have been reported in regions like the Kola Peninsula in Russia and parts of Greenland. Due to its rarity and specific formation conditions, overtonite is not a widely encountered mineral.

The mineral was first described and named in honor of Professor Charles T. Overton, a noted crystallographer. Its discovery and characterization contributed to the understanding of titanium and niobium-bearing mineralogy. While not of significant economic importance due to its scarcity, overtonite is of interest to mineralogists and geologists studying the formation of rare earth elements and accessory minerals in specific rock types. Its unique composition and structure make it a subject of ongoing research in mineral physics and geochemistry.