Tarneaegu

Tarneaegu is a rare mineral species described in mineralogical literature as a hydrated aluminum silicate with iron and magnesium substituting for aluminum in the structure. It forms under metasomatic conditions in metamorphosed carbonate rocks and is notable for its layered, sheet-like framework. The name Tarneaegu combines the locality name with a term from the local language and is used as a provisional designation pending formal approval by mineralogical authorities.

Tarneaegu occurs as small, tabular crystals with monoclinic symmetry and a vitreous to pearly luster. Colors range from colorless to pale green, and crystals are typically translucent. It has a hardness around 5.5 to 6 on the Mohs scale and a specific gravity near 2.9. Analyses indicate a layered, sheet-like arrangement consistent with other hydrous aluminum silicates.

Formation and occurrence: Tarneaegu forms through hydrothermal metasomatism during regional metamorphism of aluminum-rich rocks, typically at moderate temperatures around 300–500°C and low to moderate pressures. It is most often found in contact zones where reactive fluids alter marble, calc-silicate rocks, or schist, and it is commonly associated with garnet, chlorite, and quartz.

Significance: While not economically important, tarneaegu is of interest to researchers studying metamorphic petrology and mineral structures. Its layered framework provides insights into hydration mechanisms in silicate minerals and the behavior of aluminum-rich systems under metasomatic conditions.