Uranoclite
Chemical formula: (U⁶⁺O₂)₂(OH)₂Cl₂(H₂O)₄
Uranocirite is a very rare, secondary uranium mineral, forming microscopic, yellow, tabular crystals.
Properties
- Mohs hardness
- 1.5-0
- Luster
- Vitreous to dull
- Streak
- Very pale yellow.
- Density
- 4.038
- Fracture
- Irregular/Uneven
- Transparency
- Translucent
- Crystal system
- Monoclinic
Diagnostic features
## Identification Uranocirite is identified by its characteristic appearance – tiny, tabular crystals of an intense yellow color, forming rosette-like or fan-shaped aggregates. Key is its association with other secondary uranium minerals in the oxidation zones of deposits. Due to radioactivity, it shows a strong reaction to a Geiger counter. Identification requires advanced analytical methods, such as X-ray diffraction (XRD). ## Distinguishing from Similar Minerals It can be confused with many other yellow secondary uranium minerals, such as uranophane, carnotite, or tyuyamunite. "Hand specimen" differentiation is practically impossible. Uranocirite is distinguished by its specific crystal morphology (thin tablets) and chemical composition (it is a chloride), which can only be confirmed by chemical analysis (EDS/WDS). ## Crystal Forms Crystals are very small, thin, tabular or bladed, often flattened. They usually occur in radial or fan-shaped aggregates and rosettes, as well as in the form of thin crusts.
Geological environment
## Genesis Uranocirite is a secondary mineral, forming in the oxidation zones of uranium deposits. It forms as a result of chloride-rich solutions acting on primary uranium minerals, such as uraninite. Its formation is associated with dry, desert climates, where groundwater can reach high concentrations of chlorides. ## Mineral Associations It co-occurs with other secondary uranium minerals. In the type locality (Blue Lizard Mine), it was found in association with gypsum, metauranopilite, uranopilite, and johannite. ## Localities This is an extremely rare mineral. Apart from the type locality – the Blue Lizard Mine in Red Canyon, San Juan County (Utah, USA) – its occurrence has not been reported elsewhere in the world.
Rarity
Extremely rare
For collectors
## Quality Criteria The quality of a uranocirite specimen primarily depends on the richness and aesthetics of the crystal aggregates. The most valued specimens are those with clearly formed, undamaged rosettes or fans of tiny crystals that densely cover a small piece of the host rock. A contrasting matrix can enhance visual appeal. Due to the microscopic size of the crystals, specimens are evaluated under magnification. ## Popular Localities The only known and confirmed source of uranocirite specimens is its type locality: the Blue Lizard Mine in Utah, USA. All specimens available on the collector's market originate from this single location.
Care and storage
## Cleaning Uranocirite specimens should generally not be wet cleaned. Due to its extreme softness and fragility, the only safe method for removing dust is to use a soft brush or a photographic air blower. Contact with water can lead to dissolution or damage of the delicate crystals. ## What to Avoid Absolutely avoid contact with water, acids, detergents, and all chemicals. The mineral is very soft and susceptible to mechanical damage. As a uranium mineral, it is radioactive and should be handled with appropriate precautions (avoid inhaling dust, wash hands after contact). ## Storage Uranocirite specimens should be stored in closed, stable containers (e.g., "micromount" type) to protect them from mechanical damage, dust, and moisture. They should be kept away from other minerals that could scratch them. Due to radioactivity, it should be stored away from areas of permanent human habitation.