Kelyanite

Chemical formula: (Hg₂)₂+₆Sb₃+O₆BrCl₂

Kelyanite is an extremely rare mercury and antimony oxyhalide, forming tiny, yellow crystals with an adamantine luster.

## Characteristics Kelyanite is a very rare mineral from the oxide group, chemically a complex mercury and antimony oxyhalide. It occurs as very small, isometric crystals, rarely exceeding 0.5 mm in size. Most often, it forms granular aggregates or coatings. Its crystals take the form of cubes, octahedra, or rhombic dodecahedra, often with rounded edges. ## Physical Properties This mineral is characterized by an adamantine luster and is transparent to translucent. It has a very high density, approximately 8.35 g/cm³, which is typical for mercury-containing minerals. It is relatively soft, with a Mohs hardness estimated at 3.5. It does not exhibit cleavage, and its fracture is conchoidal. ## Colors and Varieties Kelyanite has a characteristic light yellow to yellowish-orange color. No color varieties or commercial varieties are known. ## History and Name The mineral's name comes from the Kelian (or Kelyan) River in Siberia, near which it was discovered. It was described and approved as a new mineral by the International Mineralogical Association (IMA) in 1981. The discoverers were V.I. Vasiliev, Y.N. Maslennikov, and N.A. Palchik. ## Uses Due to its extreme rarity and small crystal size, kelyanite has no industrial applications. It is solely an object of scientific interest and a collector's item for specialized collectors of rare minerals.

Properties

Mohs hardness: 3.5
Luster: Adamantine
Streak: Pale yellow
Density: 8.35
Cleavage: None
Fracture: Conchoidal
Transparency: Transparent to translucent
Crystal system: Cubic

Diagnostic features

## Identification Kelyanite can be identified by its characteristic yellow color, adamantine luster, very high density, and occurrence as small, isometric crystals. Its association with other mercury and antimony minerals in a specific geological environment is a key indicator. ## Distinguishing from Similar Minerals It can be confused with other rare, yellow secondary minerals, such as kuznetsovite or shakhovite, with which it often co-occurs. Definitive differentiation requires advanced analytical methods, such as X-ray diffraction (XRD) or chemical analysis (EDS), due to visual similarity and co-occurrence. ## Crystal Forms Kelyanite crystals are isometric and belong to the cubic system. They most often take the form of cubes, octahedra, and rhombic dodecahedra. They often have rounded or corroded surfaces. They typically form fine-grained aggregates and coatings.

Geological environment

## Genesis Kelyanite is a secondary mineral, formed in the oxidation zones of mercury-antimony deposits. It forms as a result of weathering and alteration of primary ores containing mercury, antimony, chlorine, and bromine in carbonate rocks (limestones and dolomites). ## Mineral Associations This mineral co-occurs with other rare secondary minerals of the oxidation zone, such as calomel, native mercury, eglestonite, terlinguaite, kuznetsovite, shakhovite, as well as cinnabar, native antimony, and quartz. ## Localities The most important and type locality for kelyanite is the Kelyanskoye deposit in the Chita Oblast, Eastern Siberia, Russia. This is the only confirmed and well-documented locality for this mineral worldwide.

Rarity

Very rare

For collectors

## Quality Criteria The quality of a kelyanite specimen is primarily determined by the size and development of its crystals, which is rare. Most valued are specimens with visible, sharp crystals of intense yellow color, set on a contrasting rock matrix. A rich association with other rare secondary minerals is also important. ## Popular Localities The only source of kelyanite specimens is its type locality – the Kelyanskoye deposit in Russia. All specimens available on the collector's market originate from this single location.

Care and storage

## Cleaning Due to its extreme rarity, small size, and potential toxicity (mercury content), kelyanite specimens should only be cleaned by specialists. If absolutely necessary, compressed air can be used to remove dust. Avoid contact with water and chemicals. ## What to Avoid Absolutely avoid contact with acids and other chemicals. The mineral is sensitive to heat. Due to its mercury content, avoid inhaling dust and direct skin contact. Always wash hands after handling a specimen. ## Storage Kelyanite specimens should be stored in tightly sealed, stable containers (e.g., micromount type) to prevent accidental damage and limit potential exposure to mercury vapors. Store in a dry, cool, and dark place, away from other minerals that could react chemically.

Sources

IMA Mineral List (CNMNC)