Mineraalilajin

Mineraalilajin is a mineral species described in mineralogical literature as a sheet silicate with a layered structure. It forms as fine to platy crystals in hydrothermal veins within metamorphic rocks. The mineral is typically pale green to olive and has a vitreous to pearly luster.

Occurrence and formation information indicates that minaarilajin has been reported from several Finnish localities in greenschist facies rocks, often filling fractures alongside epidote, chlorite, and quartz. It is believed to form during late-stage hydrothermal alteration of mafic rocks, with aluminum and silicon supplied by the breakdown of feldspar and pyroxene. Trace iron and magnesium can substitute into the structure, giving a range of greenish hues.

Physical and chemical properties commonly cited for minaarilajin include a hardness around 5.5–6 on the Mohs scale, a pale green to olive color, and a grayish streak. It may exhibit vitreous to pearly luster and cleave distinctly in one direction. The mineral is described as transparent to translucent in thin fragments, with a specific gravity in the approximate range of 3.0–3.4. Its composition is reported to be based on an aluminum- and silicon-oxide framework with variable substitutions by calcium and iron; there is no fixed chemical formula reported.

Taxonomy and status: The name minaarilajin derives from Finnish terms for mineral and variety, reflecting its documented occurrence in Nordic geology. As of the latest references, minaarilajin has not been officially recognized by the International Mineralogical Association, and its status remains regional and descriptive rather than formal.

See also: list of related silicate minerals and regional mineral inventories.