Aubertite

Aubertite is a rare mineral composed of barium, aluminum, and sulfate. Its chemical formula is Ba3Al2(SO4)3(OH)2·8H2O. It is known for its distinctive blue color, which is a result of the presence of copper impurities. Aubertite typically crystallizes in the monoclinic system and forms prismatic or acicular crystals. It is often found in association with other barium and aluminum minerals.

The mineral was first discovered in the early 20th century and named in honor of the French mineralogist Marcel Aubert. It is not a widely distributed mineral, with notable occurrences reported in the United States, particularly in the state of Nevada, and in other locations worldwide. The formation of aubertite is generally associated with hydrothermal alteration processes in volcanic or sedimentary rocks.

Aubertite is considered a secondary mineral, meaning it forms after the primary rocks have undergone alteration. Its properties include a Mohs hardness of around 3.5, indicating it is a relatively soft mineral. It is also characterized by its vitreous luster and its tendency to fluoresce under ultraviolet light. Due to its rarity and unique composition, aubertite is of interest to mineral collectors and researchers studying mineral formation processes. It is not typically used for commercial purposes.