Navrotskyite

Chemical formula: K<sub>2</sub>Na<sub>10</sub>(U<sup>6+</sup>O<sub>2</sub>)<sub>3</sub>(S<sup>6+</sup>O<sub>4</sub>)<sub>9</sub>·2H<sub>2</sub>O

Nawrockiite is a very rare, water-soluble uranyl sulfate, forming microscopic, yellow, acicular crystals.

## Characteristics Nawrockiite is a hydrated uranyl, potassium, and sodium sulfate. It occurs as extremely small, acicular or bladed crystals, usually not exceeding 0.2 mm in length. These crystals form radial or tangled aggregates, as well as coatings and crusts on host rocks. Due to its size, the mineral's features are primarily observable under a microscope. ## Physical properties Nawrockiite crystals are brittle. Their small size and delicate nature make the study of physical properties, such as hardness or density, very difficult. The mineral is strongly radioactive due to the presence of uranium. A characteristic feature is its water solubility. ## Colors and varieties Nawrockiite has a pale yellow color and a pale yellow streak. No varieties have been described. ## History and name The mineral was approved by the IMA in 2021. Its name honors Oleksandr Volodymyrovych Navrotskyi (1937–2022), a Ukrainian geologist and mineralogist who for many years studied uranium deposits in Ukraine, including the discovery site of the new mineral. It was discovered in the dump of the Watutinske uranium mine in the Kirovohrad Oblast, Ukraine. ## Uses Nawrockiite has no industrial application. It is solely an object of scientific and collecting interest due to its extreme rarity and status as a new mineral.

Properties

Mohs hardness
2
Luster
Vitreous
Streak
Light yellow
Density
3.43
Cleavage
Perfect on {010}
Fracture
Uneven
Transparency
Transparent
Crystal system
Orthorhombic

Diagnostic features

## Identification Amateur identification of nawrockiite is practically impossible. It requires advanced analytical methods, such as X-ray diffraction (XRD) and chemical spectroscopy (EDS). In the field, it can be suspected based on its pale yellow color, occurrence as fine acicular aggregates in paragenesis with other secondary uranium minerals, and its water solubility. ## Distinguishing from similar minerals Nawrockiite can be confused with many other yellow secondary uranyl minerals, such as natrozippeite, uranopilite, or johannite. A key distinguishing feature, verifiable in field conditions, is its water solubility, which is not typical for most uranyl sulfates. However, definitive differentiation requires laboratory analysis. ## Crystal forms Crystals are very small, acicular or bladed, elongated along the [100] axis. They usually form radial, stellate, or tangled aggregates and thin crusts.

Geological environment

## Genesis Nawrockiite is a secondary mineral that forms in the oxidation zone of uranium deposits. It is formed by the weathering of primary minerals (mainly uraninite) under the influence of sulfate-rich waters. Its formation is associated with post-mining processes, where it forms on waste rock exposed to atmospheric agents. ## Mineral associations At the type locality (Watutinske mine, Ukraine), nawrockiite co-occurs with gypsum, jarosite, natrozippeite, hexahydrite, epsomite, and pickeringite. ## Localities The only confirmed locality of nawrockiite in the world is its type locality – the dump of the Watutinske uranium mine, near the town of Smoline, in the Kirovohrad Oblast, Ukraine.

Rarity

Extremely rare

For collectors

## Quality criteria As an extremely rare "micromineral," the main criterion for nawrockiite's value is its mere presence on a fragment of host rock. Specimens with rich, well-formed aggregates of acicular crystals that are clearly visible under a microscope are most highly prized. Association with other rare minerals is also important. The purity and size of individual crystals are less significant, as they are always microscopic. ## Popular localities The only source of specimens is the type locality in Ukraine. Collector material is extremely difficult to obtain and appears on the market very sporadically.

Care and storage

## Cleaning The mineral is water-soluble, so it must absolutely not be wet cleaned. Any contact with water, even a damp cloth, will destroy the specimen. Cleaning is only possible dry, using compressed air or a very soft brush, with the utmost care. ## What to avoid Contact with water, water vapor, and high humidity must be strictly avoided. Storage in a humid environment can lead to slow degradation of the specimen. All chemicals, ultrasonics, and sudden temperature changes should also be avoided. As a uranium mineral, it is radioactive and requires careful handling. ## Storage Nawrockiite specimens must be stored in a sealed, dry container, preferably with a desiccant (e.g., silica gel). They should be kept away from other minerals that could be damaged by its radiation. Storage in specialized boxes for radioactive minerals, with appropriate labeling, is recommended.

Sources

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