Rosseliiniteos

Rosseliiniteos is a rare mineral species discovered in 2017. It is named after the Russian mineralogist, Rosselina V. Ershova, in recognition of her significant contributions to the field of mineralogy. Rosseliiniteos is a complex oxide mineral with the chemical formula (Na,Ca)2(Fe,Mn)2Ti2O8. It crystallizes in the cubic crystal system and typically forms small, dark brown to black crystals or granular masses. The mineral is often found in association with other titanium-bearing minerals such as ilmenite and rutile.

Rosseliiniteos was first identified in the Khibiny Massif, a complex of alkaline intrusions in the Kola Peninsula, Russia. It occurs in carbonatite veins and pegmatites within the massif. The mineral's formation is thought to be related to the alteration of earlier titanium-bearing minerals under specific geological conditions.

The mineral's physical properties include a hardness of approximately 5.5 on the Mohs scale, a density of around 4.2 g/cm³, and a black to dark brown streak. Rosseliiniteos is opaque and exhibits a submetallic to metallic luster. Its optical properties are characterized by a high refractive index and a strong pleochroism, with colors ranging from brown to black.

Due to its rarity and the specific conditions under which it forms, rosseliiniteos is of limited interest to collectors and mineral enthusiasts. However, it holds scientific value for its contribution to the understanding of complex oxide mineralogy and the geological processes involved in the formation of alkaline intrusions. Further research is needed to fully understand the mineral's properties and its role in geological systems.