Odikhinchaite

Chemical formula: Na₉Sr₃[(H₂O)₂Na]Ca₆Mn²⁺₃Zr⁴⁺₃Nb⁵⁺Si(Si₂₄O₇₂)O(OH)₃(CO₃)·H₂O

Odikhinchaite is an extremely rare, complex silicate with a purple color, discovered in the Khibiny Massif in Russia, distinguished by its unique chemical composition.

## Characteristics Odikhinchaite is a mineral with an exceptionally complex chemical structure, belonging to the eudialyte group. It forms small, granular aggregates, rarely exceeding 1 mm, with an intense purple or purplish-red color. Its crystals are usually poorly formed and occur as embedded grains within the rock. This mineral is valued primarily for its unique crystallochemical properties and extreme rarity. ## Physical Properties Odikhinchaite is characterized by a vitreous luster. Its Mohs hardness is approximately 5. It is a brittle mineral with an uneven fracture. The calculated density is 2.92 g/cm³. It does not exhibit cleavage. ## Colors and Varieties This mineral occurs in a characteristic purple or purplish-red color. No color varieties or commercial varieties are known. ## History and Name The mineral's name originates from the Odikhincha Massif in Krasnoyarsk Krai, Siberia, where similar eudialyte-group minerals were expected to be found. However, it was discovered in the Khibiny Massif on the Kola Peninsula in Russia. It was described by a team of mineralogists: N.V. Chukanov, I.V. Pekov, D.I. Belakovsky, and others in 2003, and approved by the International Mineralogical Association (IMA) under number 2002-068. ## Applications Due to its extreme rarity and microscopic size, odikhinchaite has no industrial applications. It is solely an object of scientific interest and a valuable acquisition for specialized collectors of rare minerals.

Properties

Mohs hardness
5
Color
deep purple
Luster
Vitreous
Streak
white
Density
2.97
Cleavage
distinct cleavage on (001)
Fracture
Irregular/Uneven
Transparency
Transparent,Translucent
Crystal system
Trigonal

Diagnostic features

## Identification Identification of odikhinchaite is almost exclusively possible using advanced analytical methods, such as infrared (IR) spectroscopy and chemical analysis (EDS/WDS). In collector conditions, identification relies on its intense purple color, vitreous luster, and co-occurrence with other minerals from the Khibiny Massif. Certain identification without specialized equipment is impossible. ## Distinguishing from Similar Minerals Odikhinchaite can be confused with other purple eudialyte-group minerals, such as raslakite or taseqite, as well as with purple fluorite or sugilite. Differentiation requires specialized studies due to similarities in color and mode of occurrence. ## Crystal Forms This mineral forms anhedral (unformed) grains up to 1 mm in size, typically as aggregates within the host rock. Well-formed, standalone crystals are not observed.

Geological environment

## Genesis Odikhinchaite forms in the late stages of crystallization of highly differentiated, alkaline magmatic intrusions. It occurs in nepheline syenite pegmatites that cut foyaite within alkaline massifs. ## Mineral Associations This mineral co-occurs with other rare alkaline minerals. In the type locality (Khibiny Massif), it was found in association with aegirine, nepheline, microcline, lamprophyllite, lorenzenite, eudialyte, delhayelite, as well as minerals from the astrophyllite and lomonosovite groups. ## Localities The only confirmed and described locality of odikhinchaite in the world is its type locality: Mount Koashva in the Khibiny Massif, on the Kola Peninsula in the Murmansk Oblast, Russia.

Rarity

Extremely rare

For collectors

## Quality Criteria The quality of odikhinchaite specimens is primarily assessed based on the intensity and saturation of the purple color and the size of the grain aggregates. The most prized specimens are those where odikhinchaite grains are clearly visible and contrast with the surrounding host rock (matrix). The presence of rare associated minerals also increases the collector's value of the specimen. ## Popular Localities The only source of odikhinchaite specimens is the Khibiny Massif in Russia. Specimens from this locality are the only ones available on the collector's market.

Care and storage

## Cleaning Odikhinchaite specimens, due to their microscopic nature and occurrence within the host rock, generally do not require cleaning. If necessary, compressed air can be used to remove dust. Avoid contact with water and any chemical agents. ## What to Avoid Avoid ultrasonic cleaners, chemical agents (acids and bases), high temperatures, and sudden thermal changes. The mineral is brittle, so it should be protected from impacts and scratches. ## Storage Specimens should be stored under stable conditions, in a closed "micromount" box, to protect them from dust and mechanical damage. It is recommended to store them in a dry place, away from direct sunlight.

External references

Sources

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