kiilleliuskeet

Kiilleliuskeet is a term used in Finnish geology to describe small expulsions or dispersions of crystal-rich material from rocks during metamorphic or hydrothermal processes. The term literally combines kiille meaning crystal or glaze and liuskeet meaning jets or eruptions, reflecting the visual appearance of brief outpourings of crystals along fractures.

In practice, kiilleliuskeet are observed as sprays or pockets of coarse or fine crystals that have crystallized rapidly and were expelled along fractures or faults in the host rock. They commonly occur in zones of contact metamorphism, pegmatitic pockets, and hydrothermal veins, where restrictive pressure drops or fluid flow promote rapid crystallization and fragmentation.

Formation mechanisms include rapid crystallization during decompression of silicate melts, fluid-assisted growth of crystals along fracture surfaces, and mechanical fragmentation of crystal-bearing veins leading to dissemination of crystals. The phenomenon can involve a range of silicate minerals, with quartz, feldspar, mica, and accessory phases frequently noted in field and lab observations.

Documentation and study rely on field observations of hand samples, thin-section petrography, scanning electron microscopy, and X-ray diffraction to characterize mineral assemblages and textures. Interpreting kiilleliuskeet can help reconstruct crystallization conditions, fluid pressures, and heating histories in metamorphic and hydrothermal systems.

See also: metamorphism, hydrothermal mineral deposits, pegmatites.