Redcanyonite

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

Redcanyonite is a very rare, secondary uranyl mineral, distinguished by its intense orange-red color and unique chemical composition.

## Characteristics Redcanyonite is a uranyl sulfate mineral that forms microscopic, tabular crystals with an intense, orange-red color. These crystals are usually aggregated into rosette-like or radial clusters, and their size rarely exceeds 0.2 mm. The mineral is transparent and exhibits a strong, vitreous luster. ## Physical Properties Due to the microscopic size of the crystals, most physical properties, such as hardness or density, have not been precisely determined. It is a soft and brittle mineral. It exhibits strong, yellow-green fluorescence under ultraviolet light (both longwave and shortwave). ## Colors and Varieties This mineral occurs in a uniform, characteristic orange-red color. No color varieties or trade names are known. ## History and Name Redcanyonite was officially recognized by the International Mineralogical Association (IMA) in 2016 (IMA2016-055). Its name comes from its discovery locality – the Red Canyon mine in San Juan County, Utah, USA. The first description was made by Anthony R. Kampf, Jakub Plášil, Travis A. Olds, and others, and the results were published in "Mineralogical Magazine" in 2017. ## Uses Redcanyonite, as an extremely rare mineral occurring in microscopic quantities, has no industrial application. It is solely of scientific interest and is a coveted object for specialized collectors of uranium minerals.

Properties

Mohs hardness
2
Luster
Vitreous
Streak
Pale orange
Density
4.13
Cleavage
Perfect on {001}
Fracture
Micaceous
Transparency
Transparent
Crystal system
Orthorhombic

Diagnostic features

## Identification Key diagnostic features include its intense orange-red color, the form of small, tabular crystals aggregated into rosettes, and strong yellow-green fluorescence under UV light. Its occurrence in association with other secondary uranium minerals is also an important clue. ## Distinguishing from Similar Minerals It can be confused with other orange or red uranyl minerals, such as metaschoepite or compreignacite. Definitive differentiation requires advanced analytical methods, such as Raman spectroscopy or X-ray diffraction (XRD), due to visual similarities and co-occurrence. ## Crystal Forms It forms thin, tabular crystals with a hexagonal outline, which combine into characteristic, radial or rosette-like aggregates. Single, well-formed crystals are extremely rare.

Geological environment

## Genesis Redcanyonite is a secondary mineral, forming in the oxidation (weathering) zone of uranium deposits. It crystallizes from the reaction of uranium-rich solutions with sulfates, in the presence of ammonia derived from the decomposition of organic matter (e.g., fossilized wood) and manganese. It forms under low-temperature conditions, on the walls of mine workings. ## Mineral Associations This mineral occurs in association with other secondary uranium minerals, such as gypsum, uranophane, johannite, as well as with manganese minerals (pyrolusite) and fossilized wood. ## Localities The only confirmed occurrence worldwide is the type locality – Red Canyon mine, White Canyon District, San Juan County, Utah, USA.

Rarity

Extremely rare

For collectors

## Quality Criteria The most highly valued specimens are those with distinct, well-formed rosette aggregates of intense, saturated color, contrasting with the rock matrix. Due to the microscopic nature of the mineral, the quality of the specimen as seen under magnification is crucial. The size and richness of the aggregates on a given piece of host rock significantly increase its value. ## Popular Localities The only source of specimens is the Red Canyon mine in Utah, USA. Material from this locality is extremely difficult to acquire and is a rarity in the collector's market.

Care and storage

## Cleaning The mineral is extremely delicate and brittle. It should not be cleaned mechanically or chemically. Any attempts at cleaning may irreversibly damage the specimen. Contact with water should be avoided. ## What to Avoid Redcanyonite is a radioactive mineral and should be handled with appropriate safety precautions. Inhaling dust and direct skin contact should be avoided. It must not be heated or exposed to chemicals. It should be protected from moisture and temperature changes. ## Storage Specimens should be stored in sealed, appropriately labeled containers, away from areas of permanent human habitation. It is best kept in a specialized collector's box (e.g., a "micromount" box), which protects delicate crystals from mechanical damage.

Sources

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