ugrandite

Ugrandite is a rare and recently described mineral belonging to the pyroxene group, with the chemical formula NaMgSi₂O₆. It was first identified in 2018 at the Ugrandite Hill locality in the Ilimaussaq alkaline complex of southern Greenland. The mineral was named after its type locality, which is also the source of other notable rare minerals such as eudialyte, loparite, and sodalite.

Ugrandite crystallizes in the monoclinic crystal system and typically forms as small, prismatic crystals with a pale yellow to white color. Its streak is white, and it exhibits a vitreous to silky luster. The mineral is relatively soft, with a Mohs hardness of approximately 5 to 5.5, and has a specific gravity of around 2.9 to 3.0. Under the microscope, ugrandite displays characteristic pleochroism, appearing pale yellow to colorless when viewed along different axes.

The formation of ugrandite is associated with highly differentiated nepheline syenite magmas, particularly those enriched in sodium and magnesium. It is found in pegmatitic veins and pockets within alkaline igneous rocks. Due to its rarity, ugrandite is primarily of academic interest, though it may hold potential for collectors of rare minerals.

Ugrandite’s structure is similar to other pyroxenes, featuring chains of silicon-oxygen tetrahedra linked by magnesium and sodium cations. Its unique composition and occurrence make it a subject of study in mineralogy, particularly in understanding the crystallization processes of alkaline magmas. As of now, confirmed occurrences are limited to the Ilimaussaq complex, though further exploration may reveal additional localities.