Xocolatlite

Chemical formula: Ca₂Mn⁴⁺₂Te⁶⁺₂O₁₂·H₂O

Xocolatlite is a rare calcium and manganese tellurate, distinguished by its characteristic chocolate-brown color and platy appearance.

## Characteristics Xocolatlite is a hydrated calcium and manganese tellurate, forming very fine, platy crystals up to 100 micrometers in size. It typically occurs as rosetted or spherical aggregates, as well as thin coatings and crusts on other minerals. Its most distinctive feature is its intense, chocolate-brown color, which inspired its name. ## Physical Properties This mineral is relatively soft, with a Mohs hardness ranging from 2 to 3. The crystals are transparent and exhibit excellent, micaceous cleavage, meaning they easily split into thin plates. Its density is quite high, approximately 4.70 g/cm³. The fracture is conchoidal. ## Colors and Varieties The main and only known color of xocolatlite is chocolate-brown. No color or commercial varieties are distinguished. ## History and Name The mineral's name comes from the Nahuatl word "xocolātl," meaning "bitter water" or "chocolate," which is a direct reference to its color. It was discovered in the Moctezuma mine in Mexico and officially described as a new mineral species in 2007, although the first finds date back to 2002. ## Uses Due to its extreme rarity and microscopic crystal sizes, xocolatlite has no industrial applications. It is solely an object of interest for collectors specializing in rare minerals or tellurate minerals.

Properties

Mohs hardness
2-3
Luster
Vitreous
Streak
Copper-brown (RAL 8004)
Density
4.70
Cleavage
mica-like
Fracture
Conchoidal
Transparency
Transparent
Crystal system
Monoclinic

Diagnostic features

## Identification Key features for identifying xocolatlite include its unique chocolate-brown color, microscopic, platy crystals forming rosetted aggregates, and a copper-brown streak. Its occurrence in paragenesis with other tellurates and tellurides in oxidized zones of hydrothermal deposits is also a strong indicator. ## Distinguishing from Similar Minerals Xocolatlite can be confused with other brown secondary minerals, such as some manganese oxides (e.g., goethite), but its characteristic luster, platy form, and co-occurrence with tellurium minerals allow for its differentiation. Final identification requires advanced analytical methods. ## Crystal Forms It forms microscopic, tabular or platy crystals that aggregate into rosetted, spherulitic, or spherical forms. It also occurs as thin coatings and earthy masses.

Geological environment

## Genesis Xocolatlite is a secondary mineral, forming in the oxidation (weathering) zone of tellurium-rich hydrothermal deposits. It forms as a result of the alteration of primary tellurides and sulfides under low temperature and pressure conditions. ## Mineral Associations It co-occurs with other rare tellurium minerals, such as schmitterite, eztlite, emmonsite, as well as quartz, barite, fluorite, and iron oxides. ## Localities The most important and typical locality for this mineral is the Moctezuma mine (Bambolla Mine) in Sonora, Mexico. This is the only confirmed locality from which well-formed specimens originate.

Rarity

Very rare

For collectors

## Quality Criteria The quality of a xocolatlite specimen primarily depends on the intensity and saturation of its brown color, and the size and definition of the rosetted aggregates. The most prized specimens are those where spherical or rosetted clusters are clearly visible, well-formed, and contrast with the light matrix rock (most often quartz). Due to the microscopic nature of the mineral, the size of individual crystals is not a key criterion. ## Popular Localities The only source of collector specimens is the type locality – the Moctezuma mine in Mexico. Specimens from this location are considered the best in the world and set the standard for this mineral.

Care and storage

## Cleaning Specimens should be cleaned very carefully, using compressed air to remove dust. Due to its softness and excellent cleavage, any mechanical contact, including cleaning with brushes or cloths, should be avoided. Contact with water is not recommended. ## What to Avoid All chemicals, acids, and detergents should be avoided. The mineral is very soft and brittle, so it must be protected from impacts, scratching, and vibrations. It should not be heated or exposed to prolonged humidity. ## Storage Xocolatlite specimens should be stored in stable conditions, preferably in a sealed "micromount" box, which protects them from dust, mechanical damage, and sudden changes in humidity. Exposure to direct sunlight should be avoided.

External references

Sources

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