Kaznakhtite
Chemical formula: Ni<sup>2+</sup><sub>6</sub>Co<sup>3+</sup><sub>2</sub>(OH)<sub>16</sub>(CO<sub>3</sub>)·4H<sub>2</sub>O
An extremely rare nickel-cobalt hydroxycarbonate, forming blue-green, tabular crystals.
Properties
- Mohs hardness
- 2 (obliczona)
- Luster
- Vitreous to Pearly
- Streak
- Pale green
- Density
- 2.81
- Cleavage
- Perfect on {0001}
- Transparency
- Translucent
- Crystal system
- Trigonal
Diagnostic features
## Identification Characteristic features of kaznakhtite include its blue-green color, the form of small, tabular crystals gathered in rosettes, and perfect cleavage in one direction. Its specific occurrence environment – fissures in chromitites – is also crucial for identification. Definitive identification requires advanced analytical methods, such as X-ray diffraction (XRD) or chemical microanalysis (EDS/WDS). ## Distinguishing from similar minerals Kaznakhtite can be confused with other secondary nickel or cobalt minerals with a green coloration. It differs from malachite by its hue (more bluish) and lack of reaction with cold hydrochloric acid. From other structurally similar minerals of the hydrotalcite supergroup (e.g., reevesite), it can only be distinguished by precise chemical composition analysis, which will show the dominance of nickel and cobalt. ## Crystal forms The mineral forms thin, hexagonal, tabular crystals. These crystals almost always occur as aggregates – most often rosettes, spherulites, or radial clusters.
Geological environment
## Genesis Kaznakhtite is a secondary mineral, formed under low-temperature hydrothermal processes. It forms in fissures and fractures of highly serpentinized ultramafic rocks, directly within chromitite bodies. ## Mineral associations This mineral occurs in association with chromite (as the host rock), as well as other rare secondary minerals such as coalingite, iowaite, and more common ones: malachite, goethite, calcite, and dolomite. ## Localities The only confirmed locality of kaznakhtite in the world is its type locality - the Kaznakht massif in the Altai Republic in southern Siberia (Russia).
Rarity
Extremely rare
For collectors
## Quality criteria As a microscopic mineral, specimens with well-formed, sharp crystals forming aesthetic rosettes or rich, dense aggregates are most highly valued. The intensity and purity of the blue-green color are important. Specimens on a contrasting chromitite matrix, with visible associations of other rare minerals, are particularly sought after by collectors specializing in mineral systematics. ## Popular localities The only source of kaznakhtite specimens is its type locality in Russia. The mineral is not commercially mined, and specimens appear on the collector's market sporadically, originating from scientific research or mineralogical expeditions.
Care and storage
## Cleaning Kaznakhtite specimens are extremely delicate due to their very low hardness and perfect cleavage. For dust removal, it is best to use compressed air or a very soft brush (e.g., squirrel hair). Wet cleaning should be avoided, and if absolutely necessary, only distilled water should be used, and the specimen should be dried immediately. ## What to avoid The mineral is sensitive to chemicals, especially acids, with which it can react as a carbonate. Ultrasonic cleaners should be avoided, as they could damage the delicate crystals. As a hydrated mineral, it is sensitive to high temperatures, which can lead to dehydration and structural damage. Protect from scratches and impacts. ## Storage It is recommended to store specimens in stable conditions, in sealed containers (e.g., micromount type), which protect against dust, mechanical damage, and sudden changes in humidity. Avoid exposure to direct sunlight.