Klausulite

Klausulite is a rare silicate mineral described from alpine metamorphic rocks. Named after the Klaus region where the type material was found, klausulite is typically considered a framework silicate with potassium and aluminum as major constituents.

Chemical composition and structure: The mineral is potassium- and aluminum-rich, with silicon and oxygen forming a tectosilicate framework. Trace elements such as iron and titanium may occur. The crystal system is monoclinic, and crystals are prismatic to tabular with a vitreous to adamantine luster.

Physical properties: Klausulite ranges in color from pale green to brown and is transparent to translucent. It has a Mohs hardness of about 6.5–7 and a specific gravity around 3.2–3.5. Cleavage is imperfect on two directions, and the mineral is typically described as having a biaxial optical character.

Occurrence and formation: Klausulite forms in high-temperature hydrothermal veins associated with granitic intrusions and in regional metamorphic rocks undergoing potassium- enrichment processes. It is commonly found with minerals such as quartz, tourmaline, and spodumene in pegmatitic or shear-zone environments.

Distribution and significance: Known occurrences are limited to the Klaus region and nearby alpine belts. Klausulite is of particular interest to mineralogical researchers and collectors as a case study in silicate framework formation and potassium-rich mineralogy. There are no widely used industrial applications reported, though its properties contribute to broader understandings of mineral classification and crystallography.