Spanoite

Chemical formula: Tl₁+₂[(U₆+O₂)₂(V₅+₂O₈)]

An extremely rare, radioactive, and toxic thallium uranyl vanadate, occurring as a secondary mineral in oxidation zones of uranium deposits.

## Characteristics Spanoite is an anhydrous thallium uranyl vanadate. Due to the presence of uranium, it is a radioactive mineral, and its high thallium content makes it highly toxic. It belongs to a very rare group of secondary minerals formed under specific geochemical conditions of oxidation zones. ## Physical Properties As a uranyl mineral, it exhibits strong radioactivity proportional to the uranium content in its crystal structure. Exact physical parameters are difficult to determine macroscopically due to the microscopic size of typical specimens. ## Colors and Varieties It has no distinct varieties. Due to belonging to the uranyl vanadate group, it assumes colors characteristic of this chemical group, most often forming fine, bright crusts. ## History and Name The type locality for this mineral is the Atlanta Mine in the Atlanta mining district (Lincoln County, Nevada, USA). It was approved as a new mineral species in recent years, making it a relatively new discovery in mineralogical systematics. ## Uses Due to its extreme rarity, spanoite has no industrial applications. It serves exclusively as an object of scientific research and an extremely rare item for advanced systematic mineral collectors.

Properties

Crystal system: Monoclinic

Diagnostic features

## Identification Visual identification is practically impossible without advanced analytical techniques, such as X-ray diffraction (XRD) or energy-dispersive X-ray spectroscopy (EDS). Field clues include a strong radiometric anomaly and co-occurrence with other secondary uranium minerals at the Atlanta Mine. ## Distinguishing from Similar Minerals Spanoite is chemically and structurally similar to other minerals in the carnotite group and related uranyl vanadates. Definitive distinction from minerals such as carnotite, tyuyamunite, or margaritasite requires chemical analysis confirming the presence of thallium as the main cation in the structure. ## Crystal Forms It forms microscopic crystals and fine aggregates typical of secondary uranyl minerals crystallizing in rock voids and fractures.

Geological environment

## Origin It is a secondary mineral crystallizing in the oxidation zones of ore deposits. It forms as a result of weathering of primary uranium and vanadium minerals in the presence of solutions rich in thallium ions. ## Mineral Associations It co-occurs with other secondary uranium and vanadium minerals characteristic of the oxidation zone of the deposit at the Atlanta Mine. ## Localities The only confirmed occurrence (type locality) is the Atlanta Mine in Lincoln County (Nevada, USA).

Rarity

Extremely rare

For collectors

## Quality Criteria For such rare minerals, the sole criterion for collector value is confirmed specimen authenticity, ideally supported by analytical test results, and documented origin from the type locality. ## Popular Localities The Atlanta Mine in Nevada (USA) is the only source of specimens of this mineral on the collector market.

Care and storage

## Cleaning Specimens should not be cleaned mechanically or washed in ultrasonic cleaners due to the risk of inhaling or ingesting toxic and radioactive dust. Any handling should be kept to an absolute minimum. ## What to Avoid Crushing, rubbing, and contact with water, which could dissolve or leach toxic thallium and uranium compounds, must be strictly avoided. Direct skin contact should be avoided, and air in the immediate vicinity of an unprotected specimen should not be inhaled. ## Storage It requires storage in airtight, transparent containers (e.g., micromount boxes), which prevents the spread of dust and limits radiation exposure. Containers should be clearly labeled as radioactive and toxic material and stored in a well-ventilated room away from living spaces.

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External references

https://www.mindat.org/min-499395.html