parraallanite

Parraallanite is a rare earth element mineral belonging to the allanite group. Its chemical formula is Ca(REE,Ca,Na)$_2$(Al,Fe$^{3+}$)$_3$(SiO$_4$)$_3$(OH). Parraallanite is characterized by a high content of rare earth elements, particularly light rare earth elements. It crystallizes in the monoclinic crystal system and typically forms prismatic or equant crystals. Its color can vary, often appearing as shades of brown, black, or reddish-brown. Parraallanite is found in a variety of igneous and metamorphic rocks, including granites, syenites, and metamorphic schists. It is often associated with other rare earth minerals and silicate minerals. The mineral was first described in 2013 from samples collected in the Paraná State of Brazil, hence its name. Due to its rarity and the dispersed nature of rare earth elements within its structure, parraallanite is not currently considered a significant economic source of these elements. Its primary importance lies in mineralogical research and understanding the complex geochemistry of rare earth element occurrences in geological environments.