Dymkovite

Chemical formula: Ni<sup>2+</sup>(U<sup>6+</sup>O<sub>2</sub>)<sub>2</sub>(As<sup>3+</sup>O<sub>3</sub>)<sub>2</sub>·7H<sub>2</sub>O

Dymkovite is a very rare secondary nickel, uranium, and arsenic mineral, forming microscopic, acicular yellow crystals.

## Characteristics Dymkovite is a hydrated uranyl nickel arsenite, occurring in the oxidation zones of uranium deposits. It forms extremely fine, acicular or capillary crystals, which usually do not exceed 0.2 mm in length and are only a few micrometers thick. These crystals form radial or tangled aggregates, as well as spherical clusters with a silky luster. Due to the microscopic size of the crystals, its features are difficult to observe without specialized equipment. ## Physical Properties Dymkovite crystals are elastic and flexible. Hardness and density have not been precisely measured due to the small size and fragility of the crystals. The mineral exhibits strong, green fluorescence under ultraviolet light. ## Colors and Varieties Dymkovite has a characteristic, bright yellow or canary yellow color. No varieties are distinguished. ## History and Name The mineral was discovered in the oxidation zone of a uranium deposit in the Labe mountain range in the Czech Republic. It was described and approved by the International Mineralogical Association (IMA) in 2015. The name honors Nikolai Mikhailovich Dymkov (1929–2013), a Russian mineralogist who made significant contributions to the study of uranium mineralogy, including the deposits where the new mineral was found.

Properties

Luster
Silky
Streak
Yellow
Transparency
Translucent
Crystal system
Monoclinic

Diagnostic features

## Identification Identification of dymkovite is possible almost exclusively using advanced analytical methods, such as Raman spectroscopy and X-ray diffraction (XRD). Visually, it is characterized by its canary yellow color, acicular crystal habit, and strong green fluorescence under UV light. ## Distinguishing from Similar Minerals It can be confused with other secondary uranium minerals of similar color and form, such as uranophane, studtite, or some zeolites. Differentiation requires specialized studies, as macroscopic physical characteristics are very similar. ## Crystal Forms Dymkovite forms exclusively very fine, acicular or capillary crystals, gathered in radial, tangled, or spherical aggregates.

Geological environment

## Genesis Dymkovite is a secondary mineral, forming in the oxidation zones of hydrothermal polymetallic deposits rich in uranium, nickel, and arsenic. It crystallizes under low-temperature conditions from aqueous solutions. ## Mineral Associations It occurs in association with other secondary uranium and arsenic minerals. In its type locality (Labe, Czech Republic), it was found in association with gypsum, annabergite, erythrite, arsenolite, pharmacolite, as well as rare uranyl arsenates like heinrichite or kahlerite. ## Localities The only confirmed occurrence of dymkovite in the world is its type locality – a uranium deposit in the Labe mountain range, near the town of Horní Slavkov in the Czech Republic.

Rarity

Extremely rare

For collectors

## Quality Criteria As a microscopic mineral, dymkovite is valued primarily by collectors specializing in "micromounts" and systematic minerals. The value of a specimen is determined by the abundance and aesthetics of the acicular crystal aggregates on the rock matrix, as well as the presence of associated minerals. The best specimens have well-formed, radial clusters of intense, yellow color.

Care and storage

## Cleaning Dymkovite specimens are extremely delicate and fragile. They should not be cleaned mechanically or chemically. Any attempt at cleaning, even with an air stream, risks destroying the microscopic crystals. ## What to Avoid Absolute avoidance of contact with water and chemicals is necessary. The mineral is sensitive to changes in humidity and temperature. As a uranium mineral, it is radioactive and toxic due to its arsenic content – avoid inhaling dust and direct skin contact. Always wash hands after handling a specimen. ## Storage Specimens should only be stored in specialized, airtight containers (so-called "micromount boxes") to protect them from mechanical damage, dust, and moisture. Store away from areas where people reside, due to radioactivity.

Sources

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