Belakovskiite
Chemical formula: Na<sub>7</sub>(U<sup>6+</sup>O<sub>2</sub>)(S<sup>6+</sup>O<sub>4</sub>)<sub>4</sub>(S<sup>6+</sup>O<sub>3</sub>OH)·3H<sub>2</sub>O
Belakovskiite is an extremely rare, water-soluble uranyl sulfate, forming bright yellow, acicular crystals and efflorescences.
Properties
- Luster
- Vitreous
- Streak
- Pale yellow
- Transparency
- Transparent to translucent
- Crystal system
- Monoclinic
Diagnostic features
## Identification Belakovskiite can be identified by its characteristic form – it creates delicate, acicular or fibrous crystals gathered in radial aggregates. Key features include its bright yellow color, strong UV fluorescence, and water solubility. It occurs in paragenesis with other secondary uranyl sulfates. ## Distinguishing from Similar Minerals It can be confused with other secondary, acicular uranyl minerals, such as zippeite, uranopilite, or johannite. Differentiation requires advanced analytical methods, such as X-ray diffraction (XRD) or chemical analysis (EDS). A key distinguishing feature in field conditions is its solubility in cold water, which is not typical for many other uranyl sulfates. ## Crystal Forms Crystals are elongated in the form of needles and fibers, often flattened. They typically form radial, stellate, or chaotically arranged aggregates, as well as delicate, fluffy efflorescences on the host rock.
Geological environment
## Genesis Belakovskiite is a secondary mineral, formed in the oxidation zones of uraninite deposits. It crystallizes under low-temperature conditions as a result of the evaporation of acidic mine waters, rich in uranium, sulfates, and sodium. Its formation is associated with mining activity, where it forms on the walls of mine workings and on waste dumps as a product of the weathering of primary minerals. ## Mineral Associations This mineral co-occurs with other secondary uranyl sulfates. At the type locality (Jáchymov), it was found in association with gypsum, adolfpaterite, svornostite, and yet undescribed mineral phases. ## Localities Confirmed occurrences of belakovskiite are limited to just a few places worldwide. The most important ones are: - Jáchymov (Svornost mine), Ore Mountains, Czech Republic - type locality. - Blue Lizard Mine, Red Canyon, San Juan County, Utah, USA. - Plavno Mine, Ore Mountains, Czech Republic.
Rarity
Extremely rare
For collectors
## Quality Criteria The most valued belakovskiite specimens are those that possess rich, well-formed, and undamaged aggregates of acicular crystals on a contrasting rock matrix. Due to its extreme rarity, any well-developed and documented specimen is valuable. Aesthetics are also important – specimens with distinct, radial "sunbursts" of crystals are particularly sought after. ## Popular Localities Specimens from the type locality in Jáchymov and from the Blue Lizard mine in Utah are the most well-known on the collector's market. Each of these locations provides specimens with slightly different characteristics, making them interesting for specialists.
Care and storage
## Cleaning The mineral must absolutely not be cleaned wet, as it is water-soluble. Specimens should only be cleaned using compressed air (from a safe distance) or a very soft brush, with utmost care due to the fragility of the crystals. ## What to Avoid Avoid contact with water and any moisture, which can dissolve and destroy the mineral. It should be protected from high temperatures and direct sunlight. As a uranium mineral, it is radioactive and requires safe handling – avoid inhaling dust and wash hands after any contact. ## Storage Belakovskiite specimens must be stored in sealed, dry containers, preferably with a desiccant (e.g., silica gel). They should be kept away from other minerals that could be damaged by its potential chemical transformations. Store in a place inaccessible to children and pets, with appropriate radioactivity labeling.