Alumoklyuchevskite

Chemical formula: K₃Cu₂+₃AlO₂(S₆+O₄)₄

An extremely rare potassium, copper, and aluminum sulfate, forming emerald-green crystals in volcanic fumaroles.

## Characteristics Alumoklyuchevskite is a mineral from the sulfate group, chemically a complex sulfate of potassium, copper, and aluminum. It occurs as small, prismatic or acicular crystals, rarely exceeding 1 mm in length. It most commonly forms radial or fan-shaped aggregates, as well as crusts on porous volcanic substrate (scoria). Its most distinctive feature is its intense, emerald-green to dark-green color. ## Physical Properties This mineral is characterized by a vitreous luster. It is transparent to translucent. Its calculated density is approximately 3.05 g/cm³. Due to its small size and rarity, many of its physical properties, such as hardness, have not been thoroughly investigated. ## Colors and Varieties Alumoklyuchevskite occurs in a uniform, characteristic color, from emerald-green to dark-green. No color varieties or commercial names are known. ## History and Name The mineral was officially described in 1999 by Lyudmila Pavlovna Vergasova and her team. The name refers to its chemical composition – the presence of aluminum (Latin: *aluminium*) – and its structural and chemical similarity to the mineral Klyuchevskite. Klyuchevskite, in turn, was named after the Klyuchevskaya Sopka volcano in Kamchatka, the region where both minerals were discovered. ## Uses Due to its extreme rarity and occurrence as microscopic crystals, alumoklyuchevskite has no industrial applications. However, it is an object of scientific interest and a valuable acquisition for specialized collectors of rare minerals.

Properties

Luster: Vitreous
Streak: Light green
Density: 3.05
Cleavage: None
Fracture: Uneven
Transparency: Transparent to translucent
Crystal system: Monoclinic

Diagnostic features

## Identification Key features for identifying alumoklyuchevskite are its emerald-green color, mode of occurrence (radial aggregates of acicular crystals), and unique geological environment – volcanic fumaroles. Certain identification is almost exclusively possible based on knowledge of its origin (Tolbachik volcano). ## Distinguishing from Similar Minerals This mineral can be confused with other green copper sulfates found in the same environment, such as Klyuchevskite. Differentiation with the naked eye is practically impossible. Klyuchevskite does not contain aluminum, so definitive distinction requires advanced analytical methods such as X-ray microanalysis (EDS/WDS) or X-ray diffraction (XRD). ## Crystal Forms Alumoklyuchevskite forms elongated, prismatic to acicular crystals. They rarely occur individually, most often growing together into radial, stellar, or fan-shaped aggregates, and also forming thin crusts and coatings.

Geological environment

## Genesis Alumoklyuchevskite is an exhalative mineral. It forms by sublimation from hot volcanic gases in an oxygen-rich environment. It crystallizes on fumarole walls and on fragments of volcanic lava at relatively high temperatures, estimated at 150-400°C. ## Mineral Associations This mineral occurs in association with other rare products of volcanic exhalations. Its most common associated minerals include Klyuchevskite, Ponomarevite, Langbeinite, Tenorite, Hematite, as well as Halite and Sylvite. ## Localities Alumoklyuchevskite is known exclusively from one location in the world – its type locality. It was found in the Arsenatnaya fumarole, on the second slag cone of the North Breakthrough of the Great Tolbachik Fissure Eruption, on the Tolbachik volcano (Kamchatka, Russia).

Rarity

Extremely rare

For collectors

## Quality Criteria The quality of alumoklyuchevskite specimens, which are almost exclusively micromounts, is assessed based on several criteria. The most important are the abundance of the mineral on the matrix and the size and development of individual aggregates. Specimens with distinct, radial structures of an intense emerald-green color are more highly valued. The presence of well-defined crystals of other rare associated minerals is an additional advantage. ## Popular Localities The only source of alumoklyuchevskite specimens is its type locality on the Tolbachik volcano in Kamchatka. All specimens available on the collector's market originate from this single location and are acquired during specialized scientific expeditions.

Care and storage

## Cleaning Alumoklyuchevskite specimens are extremely delicate and potentially water-soluble. Cleaning should be kept to an absolute minimum. Only very careful dust removal with a soft, dry brush or a gentle stream of compressed air from a distance is permissible. ## What to Avoid Contact with water, chemical solutions, and especially acids, must be strictly avoided. The mineral is unstable in a humid environment and can degrade. It should be protected from high temperatures, rapid temperature changes, and direct sunlight. Ultrasonic cleaners are prohibited. ## Storage It is recommended to store specimens in sealed containers (e.g., "perky box" type) that protect against moisture and airborne contaminants. The best environment is a stable, dry place at a constant temperature, away from light sources.

Sources

IMA Mineral List (CNMNC)