Cuyaite

Chemical formula: Ca<sub>2</sub>Mn<sup>3+</sup>As<sup>3+</sup><sub>14</sub>O<sub>24</sub>Cl

An extremely rare manganese and calcium arsenate, forming microscopic, dark red crystals with a regular structure.

## Characteristics Kujait is a mineral from the oxide group, more specifically a complex manganese and calcium arsenate. It occurs as very small, well-formed, isometric crystals, whose size does not exceed 0.1 mm. These crystals have an intense, dark red color and exhibit a strong, almost metallic luster. ## Physical Properties Kujait crystals are brittle. Due to the microscopic size of the grains, precise determination of many physical properties, such as hardness or density, is difficult. The density was calculated based on the formula and unit cell parameters and is approximately 4.55 g/cm³. ## Colors and Varieties This mineral is monochromatic – it occurs exclusively in a dark red color. No varieties are known. ## History and Name Kujait was discovered in the Torrecillas mine in the Iquique Province, Chile, and described in 2015 by Anthony R. Kampf and his team. The mineral's name comes from the Cuya geological formation, where the discovery site (type locality) is located. It was approved by the International Mineralogical Association (IMA) under number 2014-091. ## Applications Kujait has no industrial applications. Its significance is purely scientific and for collectors, as a unique and newly discovered mineral.

Properties

Luster
Submetallic
Streak
Red
Density
4.55
Cleavage
None
Fracture
Uneven
Transparency
Translucent to opaque
Crystal system
Cubic

Diagnostic features

## Identification Identification of kujait is possible only through advanced analytical methods, such as Raman spectroscopy or chemical analysis using an electron microprobe (EDS). Visually, at the occurrence site, it can be suspected based on its dark red color and co-occurrence with other rare arsenates. ## Distinguishing from Similar Minerals It can be confused with other microscopic, red secondary minerals, such as some arsenates (e.g., erythrite) or oxides (e.g., cuprite). Certain distinction requires specialized chemical analysis, which will show the presence of calcium, manganese, and arsenic in characteristic proportions, as well as chlorine. ## Crystal Forms Kujait forms very small, single crystals with a regular (isometric) structure, most often in the form of rhombic dodecahedra {110}.

Geological environment

## Genesis Kujait is a secondary mineral, formed in the oxidation zone (gossan) of a polymetallic deposit under extremely arid climatic conditions. It formed as a result of the alteration of earlier arsenical ore minerals, in the presence of solutions rich in calcium and chlorine. ## Mineral Associations This mineral occurs in association with other rare secondary minerals, such as torrecillasite, prosopite, hematite, anhydrite, quartz, and unidentified calcium and manganese arsenates. ## Localities The only confirmed locality of kujait in the world is its type locality – the Torrecillas mine, located approximately 90 km east of Iquique, in the Tarapacá Region, Chile.

Rarity

Extremely rare

For collectors

## Quality Criteria As a "micromount" type mineral, the quality of a specimen is primarily determined by the abundance and quality of crystals on the rock matrix. Specimens with numerous, sharp, well-formed crystals of intense red color, clearly contrasting with the substrate, are most valued. Confirmation of the mineral's identification is also important. ## Popular Localities The Torrecillas mine in Chile is the sole source of kujait specimens, which makes every specimen from this locality extremely valuable for specialized collectors of rare and "micromount" minerals.

Care and storage

## Cleaning Kujait specimens should not be cleaned mechanically or chemically due to their extreme rarity and microscopic crystal size. Any attempts at cleaning may irreversibly damage the mineral. It is safest to leave it in an untouched state. ## What to Avoid Avoid contact with any chemicals, ultrasound, and any mechanical stress (abrasion, impact). The mineral is brittle and very small, making it easy to damage or lose. ## Storage Specimens should be stored exclusively in specialized "micromount" boxes, protecting them from dust, moisture, and mechanical damage. Display should be away from sources of vibration and direct sunlight.

Sources

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