Mineevite-(Y)

Chemical formula: Na₂₅BaY₂(CO₃)₁₁(HCO₃)₄(S⁶⁺O₄)₂F₂Cl

Mineevite-(Y) is a very rare, complex sodium, barium, and yttrium carbonate, forming transparent, light green or yellowish-green crystals.

## Characteristics Mineevite-(Y) is an exceptionally complex and rare mineral from the carbonate group, distinguished by its intricate chemical composition, including sodium, barium, yttrium, as well as carbonate, bicarbonate, sulfate, fluoride, and chloride anions. Typical specimens form small, tabular or short-prismatic crystals with a hexagonal outline. Its unique structure and composition make it a subject of scientific interest. ## Physical Properties This mineral is characterized by a Mohs hardness of 4, placing it among relatively soft minerals. Its density is approximately 2.85 g/cm³. The crystals are transparent and exhibit a vitreous luster. It possesses perfect cleavage in one plane, which is visible in some specimens. ## Colors and Varieties Mineevite-(Y) occurs in shades from pale green to yellowish-green. No distinct color varieties or commercial varieties have been identified. ## History and Name The mineral was named in honor of Dmitry Andreevich Mineev (1935-1992), a Russian mineralogist and geochemist who made significant contributions to the study of rare earth elements in minerals. It was first discovered and described in the Lovozero Massif in Russia. ## Uses Due to its extreme rarity, mineevite-(Y) has no industrial applications. It is of purely scientific significance and is a highly prized acquisition for specialized collections of rare minerals.

Properties

Mohs hardness
4
Luster
Vitreous
Density
2.85
Cleavage
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Fracture
Step-Like
Transparency
Transparent
Crystal system
Hexagonal

Diagnostic features

## Identification Mineevite-(Y) can be identified by its characteristic hexagonal crystal shape, light green or yellowish-green color, transparency, and occurrence in a specific geological environment (agpaitic pegmatites). It reacts with acids, which is a characteristic of carbonates. ## Distinguishing from Similar Minerals It can be confused with other rare carbonates from the Lovozero Massif. Final identification requires advanced analytical methods, such as X-ray diffraction (XRD) or chemical analysis (EDS/WDS), due to its unique and complex composition. ## Crystal Forms It forms well-developed, tabular or short-prismatic crystals with a hexagonal outline, consistent with its hexagonal symmetry. It occurs as single crystals or small clusters thereof.

Geological environment

## Genesis Mineevite-(Y) forms under very specific geochemical conditions, in highly differentiated, strongly alkaline pegmatites (agpaitic pegmatites) associated with nepheline syenite intrusions. It is a late-stage crystallization mineral in these formations. ## Mineral Associations This mineral co-occurs with other rare alkaline minerals typical of the Lovozero Massif pegmatites. Its associated minerals include natrite, trona, thermonatrite, aegirine, microcline, and nepheline. ## Localities The only confirmed and type locality for mineevite-(Y) is Mount Alluaiv in the Lovozero Massif, on the Kola Peninsula in the Murmansk Oblast, Russia. This is one of the world's most famous localities for rare minerals.

Rarity

Very rare

For collectors

## Quality Criteria The most valuable specimens for collectors are those with well-formed, sharp, and undamaged crystals of distinct hexagonal shape. The intensity of color (the livelier the shade of green, the better), transparency, and crystal size are highly prized. Specimens on a rock matrix, in association with other rare minerals, are particularly sought after. ## Popular Localities The only source of collectible specimens is Mount Alluaiv in the Lovozero Massif, Russia. Material from this locality is considered classic and is the standard for this species.

Care and storage

## Cleaning Specimens should be cleaned very carefully, using only a soft brush to remove dust. Due to the presence of water-soluble bicarbonate groups, contact with water and other liquids should be avoided. ## What to Avoid Contact with water, acids, and other chemicals that can damage or dissolve the mineral must be absolutely avoided. It is sensitive to scratches due to its low hardness. It should be protected from high temperatures and sudden temperature changes. ## Storage It is recommended to store specimens under stable conditions, in closed, padded boxes or display cases, away from dust, humidity, and direct sunlight. It is best to store it in a dry environment.

External references

Sources

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