Cuzticite

Chemical formula: Fe<sup>3+</sup><sub>2</sub>Te<sup>6+</sup>O<sub>6</sub>·3H<sub>2</sub>O

Cuzticit is a rare iron tellurate, forming microscopic, yellow hexagonal crystals.

## Characteristics Cuzticit is a hydrated iron tellurate, occurring as small, hexagonal tabular crystals, rarely exceeding 0.2 mm in size. It typically forms rosetted aggregates, thin coatings, or appears as disseminated clusters on the surface of the host rock. Its intense yellow to yellow-orange color makes it easily noticeable despite its small size. ## Physical Properties Cuzticit crystals exhibit a vitreous or slightly pearly luster. They are transparent to translucent. Due to the microscopic size of the crystals, determining hardness and density is difficult; the calculated density is 3.55 g/cm³. The mineral shows perfect cleavage in one plane, parallel to the base of the tabular crystals. ## Colors and Varieties This mineral occurs in shades from golden-yellow to orange-yellow. No color varieties or commercial forms are known. ## History and Name The name "cuzticit" comes from the Nahuatl word "cuztic," used by the Aztecs, which means "yellow," directly referencing the mineral's characteristic color. It was first described in 1979 by S.A. Williams based on samples from the Bambollita mine in Moctezuma, Sonora state, Mexico. ## Uses Cuzticit has no industrial applications. Its significance is purely scientific and collectible, being an object of interest for specialized collectors of rare minerals.

Properties

Mohs hardness
3
Luster
Vitreous, Pearly
Streak
Pale yellow
Density
3.55
Cleavage
Perfect on {0001}
Fracture
Micaceous
Transparency
Transparent to translucent
Crystal system
Trigonal

Diagnostic features

## Identification Cuzticit can be identified by its characteristic golden-yellow color, hexagonal outline of small crystals, and the formation of rosetted aggregates. Its occurrence in the oxidation zones of tellurium deposits is a key indicator. ## Distinguishing from Similar Minerals It can be confused with other secondary yellow tellurium minerals, such as emmonsite or mackayite. Definitive differentiation requires advanced analytical methods, such as X-ray diffraction (XRD), due to visual similarity and co-occurrence. However, its hexagonal crystal form is a distinguishing feature. ## Crystal Forms It forms very small, thin, tabular crystals with a hexagonal outline. These crystals often combine into rosetted or radial aggregates, and also form thin coatings and crusts.

Geological environment

## Genesis Cuzticit is a secondary mineral formed in the oxidation zones of hydrothermal tellurium-rich deposits. It forms as a result of the weathering of primary tellurides under low temperature and pressure conditions. ## Mineral Associations It most often co-occurs with other tellurates and tellurides. Typical associated minerals include: native tellurium, emmonsite, schmitterite, mackayite, quartz, baryte, and iron oxides (e.g., hematite). ## Localities The most important and type locality (localitas typica) is the Bambollita (La Oriental) mine in Moctezuma, Sonora state, Mexico. This is the main locality from which the best-formed specimens originate. Outside of Mexico, its presence has been reported in the Grand Central mine in the Tombstone Mountains, Arizona, USA.

Rarity

Very rare

For collectors

## Quality Criteria The collector's appeal of cuzticit depends on several factors. Specimens with well-formed, sharp crystals forming aesthetic, rosetted aggregates are most highly valued. The intensity and saturation of the golden-yellow color also increase value. Contrast with the host rock and the absence of damage to the delicate crystals are important. Due to the microscopic nature of the mineral, the size of the aggregates and the abundance of occurrence on a given specimen are crucial. ## Popular Localities By far the most sought-after and valued specimens come from the type locality – the Bambollita mine in Moctezuma, Mexico. Specimens from this location are considered the global standard for this mineral.

Care and storage

## Cleaning Due to the extreme fragility and small size of the crystals, mechanical cleaning is not recommended. If necessary, compressed air can be used from a safe distance to remove loose dust particles. Any contact with water or other liquids is risky. ## What to Avoid Avoid contact with water and all chemicals. The crystals are very brittle and susceptible to mechanical damage, so touching, vibrations, and ultrasound should be avoided. Do not expose the specimen to sudden temperature changes. ## Storage Cuzticit specimens should be stored exclusively in stable, sealed "micromount" boxes that protect them from dust, physical damage, and moisture. Display should be away from direct sunlight and heat sources.

Sources

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