Tolbachite

Tolbachite is a rare mineral composed of copper(I) chloride, with the chemical formula CuCl. It crystallizes in the cubic system, often forming small, transparent to translucent, vitreous crystals. The color of tolbachite typically ranges from white to pale yellow or greenish. It is known for its relatively low hardness and is soluble in water and ammonia.

The mineral was first discovered in 1975 during the eruption of the Plosky Tolbachik volcano in Kamchatka, Russia, which is how it derives its name. It forms under high-temperature, fumarolic conditions, often associated with volcanic activity. Tolbachite is frequently found in association with other copper-bearing minerals and volcanic sublimates, such as anhydrite, gypsum, and thenardite.

Due to its rarity and the specific environmental conditions required for its formation, tolbachite is not an economically significant mineral. However, it is of interest to mineralogists and geochemists studying volcanic processes and the behavior of chloride minerals under extreme conditions. Its presence can provide clues about the temperature, pressure, and chemical environment within active volcanoes.