Meitnerite

Chemical formula: (N<sup>3-</sup>H<sub>4</sub>)(U<sup>6+</sup>O<sub>2</sub>)(S<sup>6+</sup>O<sub>4</sub>)(OH)·2H<sub>2</sub>O

Meitnerite is a rare, secondary uranyl mineral, distinguished by its intense yellow color and occurrence as small, tabular crystals.

## Characteristics Meitnerite is a hydrated uranyl ammonium hydroxyl sulfate. It forms very small, thin, tabular crystals, not exceeding 0.2 mm in size, which often arrange into rosetted or fan-shaped aggregates. Due to its chemical composition, this mineral is highly radioactive. ## Physical Properties Meitnerite crystals exhibit a vitreous luster. They are brittle, and their hardness and density have not been precisely determined due to their small size and rarity. It is a fluorescent mineral, glowing bright green under ultraviolet light (both longwave and shortwave). ## Colors and Varieties Meitnerite has a characteristic, intense yellow color. No varieties have been distinguished. ## History and Name The mineral was approved by the International Mineralogical Association (IMA) in 2017. Its name honors Lise Meitner (1878–1968), an Austrian-Swedish nuclear physicist who made crucial contributions to the discovery and explanation of nuclear fission. The discovery was made on archival material from the Schmied uranium mine in the Czech Republic. ## Uses Meitnerite, due to its extreme rarity, small crystal size, and radioactivity, is of purely scientific and collector's interest for specialized uranium mineral collectors.

Properties

Mohs hardness
2
Luster
Vitreous
Streak
Pale yellow
Density
3.73
Cleavage
Perfect on {010}
Fracture
Uneven
Transparency
Transparent to translucent
Crystal system
Orthorhombic

Diagnostic features

## Identification Key diagnostic features of meitnerite include its intense yellow color, thin tabular crystal habit forming fan-shaped aggregates, and strong, green fluorescence under UV light. Its occurrence in paragenesis with other secondary uranium minerals is also an important indicator. ## Distinguishing from Similar Minerals Meitnerite can be confused with other secondary, yellow uranyl minerals such as uranophane, zippeite, or meta-autunite. Distinguishing it requires advanced analytical methods, such as Raman spectroscopy or X-ray diffraction (XRD), as visual characteristics are often ambiguous. The characteristic chemical composition (presence of the ammonium group) is a unique feature. ## Crystal Forms This mineral forms very thin, tabular crystals with a rhombic or lamellar outline. These crystals almost always occur as fan-shaped, radial, or rosetted clusters and aggregates.

Geological environment

## Genesis Meitnerite is a secondary mineral, forming in the oxidation zones of uranium deposits. It crystallizes as a result of weathering processes of primary uranium minerals (such as uraninite) in the presence of sulfates and ammonium compounds. Its formation is associated with specific geochemical conditions prevailing in mine dumps and workings. ## Mineral Associations Meitnerite co-occurs with other secondary uranium minerals, such as adolfpateraite, gypsum, zippeite, uranopilite, johannite, and uraninite (as a primary mineral). ## Localities The only confirmed locality (type locality) for meitnerite is the Schmied mine in Jáchymov (St. Joachimsthal) in the Czech Republic. The mineral was found on old mine dumps.

Rarity

Extremely rare

For collectors

## Quality Criteria The collector's appeal of meitnerite depends on the richness and aesthetics of the crystal aggregates on the rock matrix. Specimens with clearly formed, fan-shaped or rosetted clusters of intense yellow color are most valued. Due to the microscopic size of the crystals, quality assessment is performed under magnification. Contrast with the dark host rock enhances visual appeal. ## Popular Localities The only source of meitnerite specimens is its type locality – the historic Schmied uranium mine in Jáchymov, Czech Republic. All specimens available on the collector's market originate from this single location.

Care and storage

## Cleaning Meitnerite specimens are generally not cleaned due to their fragility and small size. Any attempts at mechanical or chemical cleaning can irreversibly damage the delicate crystals. If absolutely necessary, compressed air can be used from a safe distance to remove dust. ## What to Avoid Contact with water, chemicals, ultrasound, and all forms of mechanical cleaning should be strictly avoided. The mineral is brittle and sensitive to temperature changes. As a uranium mineral, it is radioactive – exposure should be limited, and dust inhalation avoided. ## Storage Meitnerite must be stored in a specialized, airtight container (e.g., a "perky box") with appropriate radioactivity labeling. It should be kept away from other radiation-sensitive minerals, in a dry place with a stable temperature. Store out of reach of children and pets.

Sources

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