väljavenkite

Väljavenkite is a naturally occurring mineral belonging to the mica group. Its chemical formula is K(Li,Al)2(Al,Si3O10)(F,OH)2. It is characterized by its distinctive lilac to violet color, though it can also occur in shades of pink and gray. Väljavenkite is a phyllosilicate, meaning its structure is composed of layered sheets of silica tetrahedra.

The mineral was first described in 1935 from a specimen found in the Väljavaihe mine in the Kaavi region of Finland, hence its name. Väljavenkite is typically found in pegmatites and granite intrusions, often associated with other lithium-bearing minerals such as lepidolite and spodumene. It can also be found in some metamorphic rocks.

Crystallographically, väljavenkite is monoclinic. It typically forms in fine-grained aggregates or as small, tabular crystals. Due to its color and relatively rare occurrence, it is of interest to mineral collectors. While not economically significant, its presence can be an indicator of lithium mineralization in certain geological environments. The exact composition can vary, with substitutions of lithium and aluminum in the octahedral sites and variations in fluorine and hydroxyl content.