osalite

Osalite is a silicate mineral belonging to the phyllosilicate group, specifically classified as a hydrous magnesium aluminum silicate. It is characterized by its platy or foliated crystal habit and typically forms as a secondary mineral in serpentinite and other magnesium-rich environments.

The chemical formula of osalite is often represented as (Mg,Fe)₂Al₂Si₅O₁₆(OH)₂, indicating its composition includes magnesium, iron, aluminum, silicon, oxygen, and hydroxyl groups. Its color can vary from white to pale yellow or greenish hues, often displaying a pearly or vitreous luster on cleavage surfaces.

Osalite was first described in 1874 near Tynestead, Norway. It is associated with ultramafic rocks and is commonly found in metasomatic and hydrothermal deposits. Its structure is related to that of similar phyllosilicates, with sheets of silicate tetrahedra connected by octahedral layers containing magnesium and aluminum.

This mineral is of interest primarily to mineral collectors and researchers studying the geochemistry of serpentinites and related rocks. Although it has no significant industrial applications, its presence can provide insights into the geological history and metamorphic processes of the host rocks.

Due to its relatively rare occurrence and specific formation conditions, osalite remains a mineral of scientific interest, contributing to the understanding of mineralogical diversity within magnesium-aluminum silicate systems.