Atlasovite
Chemical formula: Cu<sup>2+</sup><sub>6</sub>Fe<sup>3+</sup>Bi<sup>3+</sup>O<sub>4</sub>(S<sup>6+</sup>O<sub>4</sub>)<sub>5</sub>·KCl
Atlasovite is an extremely rare mineral, a complex sulfate of copper, iron, and bismuth, known exclusively from volcanic exhalation products at Tolbachik volcano.
Description
## Characteristics Atlasovite is a sulfate mineral, occurring as small, well-formed crystals. It typically forms tabular or dipyramidal shapes, not exceeding tenths of a millimeter. It is observed as single crystals or small, drusy aggregates grown on porous, volcanic scoria (basalt). It is brittle and heavy due to its bismuth content. ## Physical Properties This mineral is characterized by a hardness of about 2 on the Mohs scale, making it very soft. It has a vitreous luster, transitioning to greasy on some surfaces. It is translucent in thin fragments, and in larger pieces or in mass, it becomes opaque. Its calculated density is approximately 4.21 g/cm³. ## Colors and Varieties Atlasovite has a characteristic dark color – from reddish-brown to almost black. No color or commercial varieties are known. ## History and Name The mineral was first described in 1987 by Russian mineralogists L.P. Vergasova, S.K. Filatov, E.K. Serafimova, and T.F. Semenova. Its name honors Vladimir Vasilyevich Atlasov (c. 1661-1711), a Russian explorer and one of the first researchers of the Kamchatka Peninsula, where this mineral was found. The type locality is Tolbachik volcano. ## Applications Due to its extreme rarity and microscopic crystal sizes, atlasovite has no practical applications. It is solely an object of scientific and collecting interest for specialized micromineral collectors.
Diagnostic features
## Identification Identification of atlasovite is primarily based on its unique occurrence environment – high-temperature basaltic fumaroles. Visual characteristics, such as its dark, reddish-brown color, tetragonal crystal habit (often tabular), and vitreous luster, are helpful for preliminary identification. Due to its microscopic size, definitive confirmation requires advanced analytical methods, such as X-ray diffraction (XRD) and chemical microanalysis (EDS). ## Distinguishing from Similar Minerals At the type locality, atlasovite may be confused with other dark fumarolic minerals, such as tenorite, hematite, or ponomarevite. It is distinguished from tenorite and hematite by its crystal habit and reddish hue. Differentiation from other complex sulfates from Tolbachik is impossible without specialized studies. ## Crystal Forms Atlasovite crystals are tetragonal, most often tabular, thick-tabular, or short-prismatic, terminated by pyramid faces. They occur as single, overgrown crystals or form small, crystalline aggregates and coatings.
Geological environment
## Genesis Atlasovite is an exhalative mineral. It forms through sublimation from hot volcanic gases (fumaroles) at temperatures reaching 400-600°C. It crystallizes directly on the surface of basaltic lava and tuff near exhalation vents. ## Mineral Associations This mineral occurs in association with other rare fumarolic products of Tolbachik volcano. The most common associated minerals include: hematite, tenorite, anglesite, langbeinite, nabokoite, kamchatkite, ponomarevite, sophiite, and johillerite. ## Localities The only confirmed occurrence of atlasovite in the world is its type locality – the second cinder cone of the North Breakthrough of the Great Fissure Eruption of Tolbachik (1975-1976) on the Kamchatka Peninsula in Russia.
Rarity
Extremely rare
Collector aspects
## Quality Criteria The quality of atlasovite specimens, being a micromineral, is assessed by different criteria than for macroscopic specimens. Samples with sharp, well-formed, and as large as possible crystals are most highly valued. The richness of the specimen (number of crystals on the matrix) and aesthetic associations with other rare fumarolic minerals, especially if they create a color contrast, are also important. ## Popular Localities All known atlasovite specimens collected come from a single location in the world – Tolbachik volcano in Kamchatka. It is an extremely difficult mineral to acquire, and its specimens rarely appear on the market, circulating mainly among scientific institutions and specialized micromineral collectors.
Care and storage
## Cleaning Atlasovite specimens are extremely delicate and potentially reactive. Cleaning should be limited to an absolute minimum. A soft brush or a carefully directed stream of compressed air from a safe distance can be used to remove dust. Avoid all contact with water and other liquids. ## What to Avoid This mineral is sensitive to moisture, and contact with water can lead to its damage or decomposition, similar to many other fumarolic sulfates. Avoid all chemicals, ultrasonics, temperature changes, and mechanical shocks. ## Storage Atlasovite must be stored in dry conditions. The best solution is a sealed "micromount" box, which protects the specimen from dust, moisture, and physical damage. Store at a stable temperature, away from direct sunlight.