Chukanovite

Chemical formula: Fe<sup>2+</sup><sub>2</sub>CO<sub>3</sub>(OH)<sub>2</sub>

A rare iron(II) hydroxycarbonate, forming flexible, fibrous aggregates of white, greenish, or brown color, found mainly in iron meteorites.

## Characteristics Chukanovite is a mineral from the hydroxycarbonate group, chemically a hydrated iron(II) carbonate. It most commonly occurs as radial or tangled aggregates composed of very fine, flexible fibers, which can reach up to 1 cm in length. It also forms spherulitic, rosette-like aggregates, as well as coatings and veins. Individual fibers are flexible and elastic. Due to its structure and appearance, it is sometimes mistaken for asbestos. ## Physical Properties This mineral is characterized by a silky luster, and its transparency ranges from translucent in thin fibers to opaque in massive aggregates. It is relatively soft, with a Mohs hardness of approximately 3.5. The density is variable, depending on the porosity of the aggregates, and ranges from 3.24-3.61 g/cm³. ## Colors and Varieties Chukanovite is usually white, grayish-white, or colorless. Under the influence of iron(II) oxidation to iron(III), its color changes to greenish, yellowish, and finally to reddish-brown or brown. No named varieties are distinguished. ## History and Name The mineral was approved by the IMA in 2005. Its name honors the Russian physicist and mineralogist Nikita Vladimirovich Chukanov (born 1953), a specialist in mineral infrared spectroscopy, who first described this compound. It was discovered in the Dronino iron meteorite found in Russia. ## Applications Chukanovite has no industrial applications. It is solely an object of interest for collectors specializing in rare minerals or meteoritic minerals.

Properties

Mohs hardness
3.5
Luster
Silky
Streak
White
Density
3.24-3.61
Cleavage
Perfect on {100}
Fracture
Splintery
Transparency
Translucent to Opaque
Crystal system
Monoclinic

Diagnostic features

## Identification A key diagnostic feature of chukanovite is its aggregates composed of flexible, pliable fibers, resembling asbestos or mineral wool. Its instability and tendency to change color from white to brown due to oxidation are also characteristic. It reacts vigorously with acids, releasing carbon dioxide. ## Distinguishing from Similar Minerals Chukanovite can be confused with other fibrous secondary minerals, such as serpentines (e.g., chrysotile) or asbestiform amphiboles. It is distinguished from them by its significantly lower hardness, the flexibility of its fibers, and its vigorous reaction with acids. From similar carbonates (e.g., artinite), it differs in chemical composition (presence of iron) and genesis. ## Crystal Forms Chukanovite forms exclusively fibrous, acicular, and hair-like aggregates. These aggregates often have a radial, spherulitic, or tangled habit, forming felt-like mats. It is not observed in the form of well-developed, single crystals visible to the naked eye.

Geological environment

## Genesis Chukanovite is a secondary mineral, formed by the alteration of primary minerals under specific conditions. Its main environment of occurrence is iron meteorites (octahedrites), where it forms as a product of weathering of iron-nickel alloys (kamacite and taenite) in the presence of water and carbon dioxide, under low redox potential conditions. It also forms as a result of corrosion of archaeological iron artifacts and in some hydrothermal carbonate deposits. ## Mineral Associations In iron meteorites, it coexists with kamacite, taenite, hibbingite, goethite, akaganeite, lepidocrocite, and siderite. In terrestrial environments, it is found with siderite, pyrrhotite, and magnetite. ## Localities The most important chukanovite localities are associated with meteorites. It was discovered in the Dronino meteorite (Ryazan Oblast, Russia), and also identified in the Morasko meteorite (Poland), Sikhote-Alin (Russia), and Muonionalusta (Sweden). Occurrences not associated with meteorites have been reported, among others, in Ochtinská Aragonite Cave in Slovakia and in the Kovdor alkaline complex on the Kola Peninsula in Russia.

Rarity

Very rare

For collectors

## Quality Criteria For collectors, the most valuable specimens are those with well-formed, clean fibrous aggregates, preferably of a white, unaltered (by oxidation) color. Samples where chukanovite is clearly visible against the metallic meteorite matrix are highly prized. Due to its instability, well-preserved specimens without signs of decomposition are particularly sought after. ## Popular Localities The most known and valued collector specimens come from the type locality - fragments of the Dronino meteorite found in Russia. Specimens from the Polish Morasko meteorite are also sought after by specialized collectors of meteoritic minerals.

Care and storage

## Cleaning Chukanovite specimens are very delicate and sensitive. Wet cleaning should be avoided. Only careful dust removal with a soft brush or compressed air from a safe distance is permissible. ## What to Avoid The mineral is unstable under oxidizing conditions. Contact with air, especially with moisture, causes its rapid oxidation, which manifests as a color change from white to brown and gradual decomposition into iron oxyhydroxides (e.g., goethite). Contact with water, acids, and other chemicals must be strictly avoided. It should not be heated. ## Storage Collector specimens of chukanovite require special conditions. They are best stored in sealed, clear containers (e.g., "perky boxes") with a desiccant. To slow down the oxidation process, some collectors store it under anaerobic conditions or at low temperatures. It should be protected from light and humidity changes.

External references

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