Khomyakovite

Chemical formula: Na₁₂Ca₆Sr₃Fe²⁺₃W⁶⁺Zr⁴⁺₃(Si₂₅O₇₃)(O,OH,H₂O)₃(Cl,OH)₂

Chomiakovite is a very rare, orange mineral from the eudialyte group, discovered in the famous Poudrette quarry in Canada.

## Characteristics Chomiakovite is a complex silicate belonging to the eudialyte group. This mineral forms small, granular aggregates or poorly formed crystals. Its most characteristic feature is an intense, orange to orange-red color. Specimens are usually small, embedded in the host rock. Due to its extremely rare occurrence and complex chemical composition, it is a mineral of primarily scientific and collector's interest. ## Physical Properties Chomiakovite has a hardness ranging from 5-6 on the Mohs scale. It has a vitreous luster, and its crystals can be transparent or translucent. It does not exhibit cleavage, and its fracture is uneven. The streak is white. ## Colors and Varieties This mineral occurs in uniform shades from orange to orange-red. No distinct color varieties or commercial varieties have been identified. ## History and Name The mineral's name honors the Russian mineralogist Aleksandr Petrovich Khomyakov (1933-2012), a researcher of alkaline minerals who discovered and described many new species from the Khibiny and Lovozero massifs on the Kola Peninsula. Chomiakovite was recognized as a new mineral by the International Mineralogical Association (IMA) in 1999. ## Uses Chomiakovite has no industrial applications. It is solely an object of scientific interest and for advanced collectors specializing in rare minerals or minerals from the eudialyte group.

Properties

Mohs hardness: 5-6
Luster: Vitreous.
Streak: White
Density: 0
Cleavage: None(?)
Fracture: Irregular/Uneven
Transparency: Transparent,Translucent
Crystal system: Trigonal

Diagnostic features

## Identification Chomiakovite can be identified by its characteristic orange color, vitreous luster, and occurrence in a specific geological environment (nepheline syenite pegmatites). Its granular form and lack of distinct cleavage are also helpful in identification. However, definitive confirmation requires advanced chemical analyses (EDS/WDS) due to its similarity to other minerals in the eudialyte group. ## Distinguishing from Similar Minerals This mineral is extremely difficult to distinguish from other orange or reddish members of the eudialyte group (e.g., eudialyte, manganokhomyakovite, ferrokentbrooksite) without specialized testing. The differences lie in subtle elemental proportions in the chemical composition, which cannot be verified by visual methods. ## Crystal Forms Chomiakovite most often forms anhedral (undeveloped) grains up to several millimeters in size, occurring as aggregates within the rock. Less commonly, poorly formed, platy crystals with a trigonal outline are observed.

Geological environment

## Genesis Chomiakovite crystallizes in the late stages of pegmatite evolution associated with nepheline syenite intrusions. It forms in a strongly alkaline environment, rich in sodium, zirconium, strontium, and rare earth elements. ## Mineral Associations This mineral co-occurs with other rare minerals typical of the Mont Saint-Hilaire locality. Its typical associations include other minerals from the eudialyte group, aegirine, microcline, nepheline, sodalite, catapleiite, and analcime. ## Localities The only confirmed occurrence of chomiakovite in the world is its type locality – the Poudrette quarry (Mont Saint-Hilaire) in Quebec, Canada. This is one of the most famous mineralogical sites in the world, known for the occurrence of several hundred different, often very rare, minerals.

Rarity

Extremely rare

For collectors

## Quality Criteria The most prized chomiakovite specimens are those that contain clearly visible, well-defined grains of intense, orange-red color, contrasting with the light host rock (usually white analcime or nepheline). Due to the lack of well-formed crystals, the main criteria are the size and richness of the aggregates and the intensity of the color. Specimens with visible associations of other rare minerals also increase in value. ## Popular Localities All known chomiakovite specimens come from a single location in the world: the Poudrette quarry in Mont Saint-Hilaire, Canada. Material from this locality is the standard for this mineral.

Care and storage

## Cleaning Specimens should be cleaned only very carefully, using a soft brush to remove dust. Due to its rarity and potential reactivity, contact with water and any chemical agents should be avoided. ## What to Avoid Avoid ultrasonic cleaners, chemical agents (acids, bases, solvents), and sudden temperature changes. The mineral should be protected from direct, prolonged exposure to sunlight, which could theoretically affect its color. ## Storage It is recommended to store specimens in stable conditions, in sealed "micromount" boxes, protecting them from dust, moisture, and mechanical damage. It is best to keep it away from other minerals to avoid scratches.