Hydrokenoralstonite

Chemical formula: &#9744;<sub>2</sub>Al<sub>2</sub>F<sub>6</sub>(H<sub>2</sub>O)

Hydrokenoralstonite is a very rare aluminum fluoride, forming microscopic, colorless crystals in the isometric system.

## Characteristics Hydrokenoralstonite is a hydrated aluminum fluoride belonging to the pyrochlore group. It occurs as very small, octahedral crystals, usually not exceeding 0.1 mm in size. The crystals are colorless and transparent, with a vitreous luster. Due to its microscopic size, it is a mineral difficult to observe with the naked eye and requires magnification for identification. ## Physical Properties This mineral is characterized by a hardness in the range of 4-4.5 on the Mohs scale. Its calculated density is approximately 2.72 g/cm³. The crystals exhibit a white streak and vitreous luster. No cleavage has been observed, and its fracture is uneven. ## Colors and Varieties Hydrokenoralstonite is typically colorless. No colored varieties or trade names are known. ## History and Name The mineral's name is derived from its chemical composition – indicating hydration ("hydro"), an empty site in the crystal structure ("keno"), and its relation to ralstonite. It was approved as a new mineral species by the International Mineralogical Association (IMA) in 2017 under number IMA2017-087. It was described based on material from the Zapadnaya mine in Kalush, Ukraine.

Properties

Mohs hardness
4-4.5
Luster
Vitreous
Streak
White
Density
2.72
Cleavage
None
Fracture
Uneven
Transparency
Transparent
Crystal system
Isometric

Diagnostic features

## Identification Identification of hydrokenoralstonite is possible almost exclusively through advanced analytical methods, such as Raman spectroscopy, X-ray diffraction (XRD), or chemical analysis using an electron microprobe (EDS/WDS). In collector's conditions, recognition relies on visual identification under a microscope and knowledge of co-occurring minerals from a given locality. ## Distinguishing from Similar Minerals It can be confused with other microscopic, colorless minerals from the pyrochlore group, such as ralstonite or hydrokenoelsmoreite. Definitive differentiation requires specialized laboratory tests to determine the exact chemical composition and structural parameters. ## Crystal Forms It forms very small, well-formed crystals with an octahedral habit {111}, sometimes with cubic modifications {100}. They usually occur as single, dispersed crystals on the surface of other minerals.

Geological environment

## Genesis Hydrokenoralstonite is a secondary mineral, forming in the oxidation zones of potassium- and magnesium-rich salt deposits. It forms as a result of weathering and alteration processes of primary minerals in a low-temperature environment. ## Mineral Associations This mineral co-occurs with other rare evaporite minerals. In its type locality (Zapadnaya mine, Ukraine), it was found in association with halite, sylvite, carnallite, polyhalite, gypsum, anhydrite, kainite, leonite, bischofite, epsomite, langbeinite, and ralstonite. ## Localities The only confirmed and described occurrence of hydrokenoralstonite in the world is its type locality: the Zapadnaya potash salt mine in Kalush, Ivano-Frankivsk Oblast, Ukraine.

Rarity

Extremely rare

For collectors

## Quality Criteria As a microscopic mineral, the main criterion for value for collectors is the quality and richness of the matrix specimen. The most desirable samples are those with numerous, well-formed, and sharp crystals, clearly visible against a contrasting matrix. Association with other rare minerals is also important. ## Popular Localities The only source of collector specimens is the Zapadnaya mine in Ukraine. Specimens from this locality are highly prized by collectors specializing in micromount minerals and rare species.

Care and storage

## Cleaning Due to the microscopic size and fragility of the crystals, mechanical cleaning is not recommended. If the specimen is on a stable matrix, it can be gently rinsed with distilled water and dried with compressed air. ## What to Avoid Avoid contact with acids and strong chemicals. The mineral is relatively soft, so protect it from scratches and impacts. Do not subject it to ultrasonic cleaning. ## Storage Hydrokenoralstonite specimens, due to their size, are best stored in specialized micromount boxes, which protect them from dust and mechanical damage. Avoid exposure to moisture and extreme temperatures.

Sources

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