toistolaite

Toistolaite is a rare and complex mineral discovered in the early 21st century, named after its type locality, the Toisto mine in Finland. It belongs to the class of silicates, specifically a nesosilicate, characterized by isolated silicon-oxygen tetrahedra. The mineral was first identified in 2005 and officially recognized by the International Mineralogical Association (IMA) in 2010.

Toistolaite has the chemical formula Na₃Ca₃Zr(Si₆O₁₈)·2H₂O, indicating its composition includes sodium, calcium, zirconium, silicon, oxygen, and water. It crystallizes in the hexagonal system, forming prismatic or tabular crystals that are typically translucent to transparent with a vitreous luster. The mineral exhibits a pale yellow to colorless hue and is relatively soft, with a Mohs hardness of approximately 4.5 to 5.

Toistolaite is found in alkaline pegmatites, which are coarse-grained igneous rocks formed from slowly crystallizing magma rich in silica and volatile components. The type specimen was recovered from a pegmatite dike associated with nepheline syenite at the Toisto mine in the Kola Peninsula region of Russia, near the Finnish border. Due to its rarity, toistolaite is not commonly encountered in mineral collections or research.

The mineral’s structure and composition make it of interest to geologists studying the formation of alkaline rocks and pegmatites. Its occurrence is limited to a few known localities, primarily in Russia and Finland, contributing to its status as a rare and specialized mineral. Further research on toistolaite focuses on its crystallographic properties and potential implications for understanding magmatic processes in alkaline environments.