Lenoblite

Chemical formula: V⁴⁺₂O₄·₂H₂O

Lenoblite is a rare, hydrated vanadium oxide, forming characteristic dark green to black aggregates and coatings.

## Characteristics Lenoblite is a hydrated vanadium oxide, typically occurring as earthy or compact masses, as well as crusts and coatings. It rarely forms microscopic, bladed crystals. Its appearance is inconspicuous, and specimens most often take the form of thin layers on the host rock. ## Physical Properties This mineral is relatively soft, with a hardness of about 3 on the Mohs scale. It has a vitreous or dull luster. It is opaque. Its density is higher than average, at approximately 3.43 g/cm³. ## Colors and Varieties Lenoblite occurs in shades from dark, spinach green to almost black. No color or commercial varieties are distinguished. ## History and Name The mineral's name comes from its discovery locality in the Mounana mine in Gabon, where "le noble" (French for noble) was a term for rich uranium-vanadium ore. It was first described in 1968 by French mineralogists: Fabien Cesbron and Jean-François Laurent. ## Uses Lenoblite has no industrial application. It is solely an object of interest for collectors specializing in rare minerals or vanadium minerals.

Properties

Mohs hardness: 3
Luster: Vitreous
Streak: Greenish gray
Density: 0
Cleavage: Perfect on {001}
Fracture: Uneven
Transparency: Opaque
Crystal system: Orthorhombic

Diagnostic features

## Identification Lenoblite is difficult to identify visually with certainty. It is recognized by its dark green to black color, occurrence as coatings and crusts, and association with other vanadium minerals in the oxidation zones of uranium-vanadium deposits. ## Distinguishing from Similar Minerals It can be confused with other dark-colored secondary vanadium minerals, such as doloresite, with which it often co-occurs. Definitive differentiation requires advanced analytical methods, such as X-ray diffraction (XRD). ## Crystal Forms Crystals are extremely rare and appear as microscopic, bladed forms. It typically forms earthy, compact aggregates, radial aggregates, or thin crusts.

Geological environment

## Genesis Lenoblite is a secondary mineral, formed in the oxidation zones of hydrothermal uranium-vanadium deposits. It forms as a result of the weathering of primary vanadium minerals, such as patronite or montroseite, under low temperature and pressure conditions. ## Mineral Associations It most commonly co-occurs with other vanadium and uranium minerals. Typical associated minerals include doloresite, montroseite, francevillite, as well as copper minerals like malachite. It often occurs in association with bituminous substances. ## Localities The most important and classic locality, from which the best specimens originate, is the Mounana mine in Haut-Ogooué Province, Gabon. This mineral has also been confirmed in several locations in the USA, mainly in Utah, Colorado, and Arizona, where it occurs in uranium-vanadium deposits on the Colorado Plateau.

Rarity

Very rare

For collectors

## Quality Criteria The collector appeal of lenoblite primarily depends on the richness and visibility of the crusts on the host rock. Specimens with distinct, dark green aggregates contrasting with the matrix are most desirable. Due to the rarity of well-formed crystals, even microscopic aggregates significantly increase the value of a specimen. Association with other rare minerals is also important. ## Popular Localities By far the most prized specimens come from the type locality - the Mounana mine in Gabon. Material from this mine is considered classic and serves as a reference point for this mineral.

Care and storage

## Cleaning Lenoblite specimens are very delicate and should be handled with care. Cleaning should be kept to an absolute minimum. If necessary, a soft brush can be used to remove dust. Water and any chemical agents should be avoided. ## What to Avoid The mineral is sensitive to moisture and can undergo alteration upon contact with water. Ultrasonic cleaners, all acids, detergents, and sudden temperature changes should be avoided. It should not be exposed to prolonged sunlight. ## Storage It is recommended to store specimens in dry conditions, preferably in an airtight container with a desiccant (e.g., silica gel). They should be protected from dust and mechanical damage.

External references

https://www.mindat.org/min-2376.html