Labuntsovite-Mn

Chemical formula: Na₄K₄Mn₂+₂Ti₄+₈O₄(Si₄O₁₂)₄(OH)₄·₁₀-₁₂H₂O

Labuntsovite-Mn is a rare mineral from the silicate group, forming characteristic orange or brown prismatic crystals.

## Characteristics Labuntsovite-Mn is a complex silicate of titanium, sodium, potassium, and manganese, belonging to the labuntsovite group. It forms elongated, prismatic, often acicular crystals, which can occur as radial or tangled aggregates. Specimens typically have an intense orange, reddish-brown, or yellowish-brown color. The crystals exhibit strong pleochroism, meaning a change in color depending on the viewing direction. ## Physical Properties This mineral has a hardness of approximately 6 on the Mohs scale. It has a vitreous luster, which may be more dull on fracture surfaces. It is a brittle mineral, with a density of about 2.95 g/cm³. Crystals are usually translucent, rarely transparent. ## Colors and Varieties The dominant colors are shades from orange and reddish-orange to brown and yellowish-brown. No named commercial or color varieties are distinguished. ## History and Name The mineral's name refers to its chemical composition – it is the manganese (Mn) analogue of labuntsovite. The labuntsovite group was named in honor of Russian mineralogists Alexander and Ekaterina Labuntsov. Labuntsovite-Mn was formally described as a new mineral species in 1955 by N.I. Semenov and T.A. Burovaya based on material from Khibiny on the Kola Peninsula in Russia. ## Uses Labuntsovite-Mn has no industrial application. It is valued solely as a collector's mineral due to its rarity, attractive color, and well-formed crystals.

Properties

Mohs hardness: 6
Luster: Vitreous
Streak: Pale orange
Density: 2.9-2.96
Cleavage: Good on {100}
Fracture: Uneven
Transparency: Translucent to transparent
Crystal system: Monoclinic

Diagnostic features

## Identification Labuntsovite-Mn is most easily identified by its characteristic orange to brown color, prismatic crystal habit, and occurrence in radial aggregates. An important feature is its genesis – it occurs almost exclusively in nepheline syenite pegmatites. ## Distinguishing from Similar Minerals It can be confused with other minerals from the labuntsovite group (e.g., kuzmenkoite-Mn), from which differentiation requires advanced chemical analysis (EDS/WDS). Sometimes it may resemble some eudialites or serandites, but it differs from them in crystal habit and hardness. ## Crystal Forms Crystals are typically elongated, prismatic, with a cross-section close to square. They often form radial, stellate, or chaotically tangled aggregates. Single, well-formed crystals are less common.

Geological environment

## Genesis Labuntsovite-Mn is a hydrothermal mineral, crystallizing in the late stages of the evolution of highly alkaline intrusive massifs. It forms in vugs and fissures in nepheline syenite pegmatites. ## Mineral Associations It often co-occurs with minerals such as aegirine, natrolite, analcime, microcline, nepheline, eudialyte, lorenzenite, serandite, as well as other minerals from the labuntsovite group. ## Localities The most important and classic localities for this mineral are in the alkaline massifs of Khibiny and Lovozero on the Kola Peninsula in Russia. The world's best specimens originate from there. It is also known from the Ilimaussaq complex in Greenland and from Mont Saint-Hilaire in Quebec, Canada.

Rarity

Rare

For collectors

## Quality Criteria The most prized specimens by collectors are those with sharp, well-terminated crystals of intense orange color. Radial aggregates ("sunbursts") on a light rock matrix, e.g., on white analcime or natrolite, which create an attractive contrast, are highly valued. Crystal size and the absence of mechanical damage also significantly increase the specimen's value. ## Popular Localities By far the most sought-after specimens come from the Khibiny and Lovozero massifs in Russia. Specimens from Mont Saint-Hilaire in Canada are also valued, although they often have smaller crystals.

Care and storage

## Cleaning Labuntsovite-Mn specimens should be cleaned very carefully, using a soft brush to remove dust. Brief rinsing in distilled water is permissible, followed by thorough drying. Ultrasonic cleaners should be avoided, as they can damage the brittle crystals. ## What to Avoid This mineral is sensitive to acids and strong chemicals. Prolonged exposure to direct sunlight should be avoided, as it can theoretically affect the intensity of its color. It should not be heated or exposed to sudden temperature changes. ## Storage Collector's specimens of Labuntsovite-Mn are best stored in separate, padded boxes or display cases to prevent scratches and mechanical damage. Due to its brittleness, it should be protected from impacts and falls.

Sources

IMA Mineral List (CNMNC)