Nakanalite

Nakanalite is a rare mineral classified as a sodium-rich phosphate-silicate. It was named after the Nakana Plateau in eastern Japan, where the type specimen was found, and was described in 2015 by researchers from the University of Tokyo and the National Museum of Nature and Science. The mineral occurs in late-stage granitoid pegmatites and hydrothermal veins.

Chemistry and structure: Nakanalite is dominated by sodium, aluminum, silicon, and phosphorus, with minor magnesium, calcium, and trace fluorine. The crystal structure is described as monoclinic, featuring a layered arrangement that accommodates phosphate tetrahedra linked to silicate layers. It forms prismatic or tabular crystals with a pale blue to green hue and a vitreous luster. The Mohs hardness is about 5.5, and the specific gravity is relatively modest.

Occurrence: The type material comes from pegmatitic pockets within metamorphosed granitic rocks of the Nakana region. Nakanalite is typically associated with minerals such as apatite, muscovite, spodumene, and fluorite, indicating crystallization in low-temperature, late-stage hydrothermal conditions.

Etymology and naming: The name combines the locality (Nakana) with the conventional mineral suffix -lite, reflecting its classification and origin.

Significance: Nakanalite is of interest primarily to mineral collectors and to science as it broadens the known diversity of phosphate-silicate minerals and sheds light on late-stage pegmatitic processes. Ongoing work aims to refine its precise composition, structural details, and broader occurrence.