Eliseevite

Chemical formula: Na₁.₅Li{Ti⁴⁺₂O₂[Si₄O₁₀.₅(OH)₁.₅]}·2H₂O

Eliseevite is an extremely rare mineral from the silicate group, discovered on the Kola Peninsula in Russia, forming microscopic, colorless crystals.

## Characteristics Eliseevite is an exceptionally rare, hydrated sodium, lithium, and titanium silicate. It occurs as very small, lath-like or tabular crystals, which rarely exceed 0.2 mm in length. The crystals are typically colorless and transparent, with a vitreous luster. Due to their microscopic size, its visual features are difficult to observe without specialized equipment. ## Physical Properties Eliseevite crystals are characterized by a hardness of approximately 5 on the Mohs scale. They have a vitreous luster and are transparent. The mineral's density has been calculated at 2.82 g/cm³. It is brittle and exhibits an uneven fracture. ## Colors and Varieties This mineral is typically colorless. No colored varieties or trade names have been reported, which is typical for such rare and microscopic specimens. ## History and Name Eliseevite was first described in 2009 by a team of mineralogists (V.N. Yakovenchuk et al.). The mineral is named in honor of Nikolai Alexandrovich Eliseev (1897–1966), a distinguished Russian geologist and petrologist, professor at Saint Petersburg State University, who made significant contributions to the study of the Kola Peninsula. ## Uses Eliseevite has no industrial or commercial applications. Its significance is purely scientific and collectible, as a unique and extremely rare component of the Earth's crust.

Properties

Mohs hardness
5
Color
pale creamy to colorless
Luster
Vitreous
Streak
white
Density
2.68
Cleavage
{100}
Fracture
Splintery
Transparency
Transparent
Crystal system
Monoclinic

Diagnostic features

## Identification Identification of eliseevite is impossible without advanced laboratory techniques, such as X-ray diffraction (XRD) and chemical analysis (EDS/WDS). In collector conditions, identification relies solely on trust in a label from a reputable source confirming scientific analysis. Visually, these are merely microscopic, colorless crystals on the matrix rock. ## Distinguishing from Similar Minerals Based on appearance, it cannot be distinguished from many other microscopic, colorless silicates that may coexist with it, such as quartz, albite, or microcline. The only method of differentiation is analysis of chemical composition and crystal structure. ## Crystal Forms Eliseevite forms very small, lath-like or tabular crystals, often grouped into small, radial aggregates. Crystals reach sizes up to 0.2 x 0.05 x 0.01 mm.

Geological environment

## Genesis Eliseevite forms under hydrothermal conditions, in the late stage of crystallization of highly differentiated, alkaline nepheline syenite pegmatites. It crystallizes in rock cavities and fissures from solutions rich in sodium, lithium, titanium, and silica. ## Mineral Associations This mineral coexists with other rare minerals typical of the Khibiny massif pegmatites. The most common associations include: aegirine, lorenzenite, microcline, nepheline, sodalite, eudialyte, lomonosovite, as well as rarer ones such as vuonnemite, zirsinalite, and kazakovite. ## Localities The only confirmed occurrence of eliseevite in the world is its type locality – Mount Koashva in the Khibiny massif on the Kola Peninsula in Russia. This is a classic locality for many rare alkaline minerals.

Rarity

Extremely rare

For collectors

## Quality Criteria For a mineral as rare as eliseevite, the primary criterion for value is its mere presence on the specimen, scientifically confirmed. Most highly prized are specimens where the crystals, despite their microscopic size, are as well-formed as possible, form richer clusters, and are set on an aesthetic matrix with contrasting associated minerals. Each specimen is treated as unique. ## Popular Localities The only source of eliseevite specimens is the Koashva mine in the Khibiny massif on the Kola Peninsula in Russia. Specimens from this locality are highly sought after by specialized collectors of rare minerals and micromounts.

Care and storage

## Cleaning Due to its extreme rarity, microscopic size, and delicacy, specimens containing eliseevite should not be cleaned under amateur conditions. Any attempts at cleaning, even with compressed air, risk irreversible loss of the crystals. Specimens should be left in their untouched state. ## What to Avoid Avoid any contact with chemicals, ultrasonics, water, and sudden temperature changes. The mineral is brittle, so it should be protected from shocks, impacts, and abrasions. Do not touch it to avoid contaminating the surface of the microcrystals. ## Storage Specimens containing eliseevite should be stored exclusively in specialized, sealed "micromount" boxes that protect them from dust, moisture, and mechanical damage. Store in stable room conditions, away from sources of vibration and direct sunlight.

External references

Sources

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