Pomite

Chemical formula: Ca₃[V⁴⁺₅V⁵⁺₁₀O₃₇(CO₃)]·37H₂O

Pomite is an extremely rare hydrated calcium carbonate vanadate, forming microscopic, black crystals with a metallic luster.

## Characteristics Pomite is a mineral from the vanadate group, distinguished by its exceptionally complex chemical composition, containing both tetravalent and pentavalent vanadium, as well as a carbonate group. It occurs as very small, tabular or bladed crystals, rarely exceeding 0.2 mm in length. These crystals form radial or tangled aggregates. Due to their microscopic size, visual features are difficult to observe without magnification. ## Physical Properties The crystals are too small to reliably determine their hardness or density by standard methods. They exhibit a metallic luster and are opaque. The streak is black. ## Colors and Varieties This mineral is black. No varieties are distinguished. ## History and Name Pomite was officially recognized as a new mineral by the International Mineralogical Association (IMA) in 2017. Its name honors the French mineralogist and collector Jacques Pom, in recognition of his contributions to the study of uranium and vanadium minerals. It was discovered in the Mounana uranium mine in Gabon. ## Uses Pomite has no industrial applications. Its significance is purely scientific and for collectors, as a unique and complex mineral species.

Properties

Mohs hardness
2
Color
Very dark green-blue
Luster
Metallic
Streak
Green-blue
Density
2.19
Cleavage
On {010} and {001}.
Fracture
Irregular/Uneven,Splintery
Transparency
Opaque
Crystal system
Triclinic

Diagnostic features

## Identification Identification of pomite is only possible using advanced analytical methods, such as Raman spectroscopy or X-ray diffraction (XRD), due to its microscopic size and occurrence in complex parageneses. Visually, under high magnification, black, metallic-lustrous, tabular crystals in aggregates can be observed. ## Distinguishing from Similar Minerals It can be confused with other black, fine-grained secondary minerals from oxidation zones, such as manganese oxides, shumwayite, or other complex vanadates. Definitive differentiation requires specialized chemical and structural analysis. ## Crystal Forms Pomite forms very thin, tabular or bladed crystals, flattened parallel to {010}. These crystals combine into small, radial or randomly oriented aggregates.

Geological environment

## Genesis Pomite is a secondary mineral, forming in the oxidation zones of uranium-vanadium deposits. It forms as a result of the weathering of primary ore minerals in the presence of solutions rich in vanadium and carbonates. It forms under low-temperature conditions, likely in voids and fractures of sedimentary rocks. ## Mineral Associations At the type locality (Mounana mine), it co-occurs with minerals such as francevillite, chervetite, duttonite, as well as uranium oxides and other vanadates. ## Localities The only confirmed occurrence of pomite in the world is its type locality – the Mounana mine, near Franceville, in the Haut-Ogooué Province of Gabon.

Rarity

Extremely rare

For collectors

## Quality Criteria As a "micromount" type mineral, the quality of a specimen is primarily determined by the abundance and development of its microscopic crystals. Specimens with clearly formed, undamaged crystalline aggregates, well-isolated on the rock matrix, are most valued. Contrast with associated minerals also enhances visual appeal under the microscope. ## Popular Localities The only source of specimens is the Mounana mine in Gabon, which is currently inactive. Material available on the market comes from old collections.

Care and storage

## Cleaning Specimens of pomite are extremely delicate and usually microscopic. They should not be cleaned mechanically or chemically. Any attempts at cleaning risk irreversible damage to the mineral. It is best to leave them in their untouched state. ## What to Avoid Avoid contact with water, chemicals, ultrasound, and any vibrations or impacts. Changes in temperature and humidity can be harmful. Do not expose specimens to direct sunlight. ## Storage Specimens should only be stored in specialized, sealed "micromount" boxes, protecting them from dust, moisture, and mechanical damage. Store in stable room conditions.

External references

Sources

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