Ilirneyite

Chemical formula: Mg₀.₅Zn²⁺Mn³⁺(Te⁴⁺O₃)₃·₄.₅H₂O

Ilirneyite is a very rare zinc, magnesium, and manganese tellurite, forming tiny, hexagonal crystals with a characteristic reddish-brown color.

## Characteristics Ilirneyite is a complex zinc, magnesium, and manganese tellurite, belonging to the zemannite group. It occurs as small, hexagonal, prismatic crystals, which may be terminated by pyramids. Crystals are typically very small, rarely exceeding 1 mm in length. Its appearance is distinctive due to its intense, reddish-brown color and vitreous luster. ## Physical Properties This mineral is transparent to translucent. It exhibits a vitreous luster. Its density, calculated based on the formula and cell parameters, is approximately 4.205 g/cm³. Hardness has not been precisely determined, but for other minerals in the zemannite group, it is typically around 3 on the Mohs scale. ## Colors and Varieties Ilirneyite occurs in shades ranging from reddish-brown, through dark brownish-red, to brown and light brown. No color varieties or commercial varieties have been distinguished. ## History and Name The mineral's name comes from its discovery locality – the Ilirney ore district in Chukotka, Russia. It was first described in 2003 by a team of mineralogists: N.V. Chukanov, I.V. Pekov, D.Y. Pushcharovsky, G. Giester, E. Tillmanns, A.E. Zadov, S.V. Krivovichev, and W.W. Zaykov. It was approved by the International Mineralogical Association (IMA) in 2002 (IMA2002-054). ## Uses Ilirneyite has no industrial applications. It is solely an object of interest for collectors specializing in rare minerals and scientists studying tellurium mineralogy.

Properties

Luster: Vitreous
Density: 4.205
Fracture: Irregular/Uneven
Transparency: Transparent,Translucent
Crystal system: Hexagonal

Diagnostic features

## Identification Identification of ilirneyite is based on its characteristic crystal form (hexagonal prisms), intense reddish-brown color, and vitreous luster. However, its association with the locality is crucial – it occurs in the oxidation zones of tellurium deposits. Final identification requires advanced analytical methods, such as X-ray diffraction (XRD) and chemical analysis (EDS/WDS). ## Distinguishing from Similar Minerals Ilirneyite can be confused with other minerals from the zemannite group, such as zemannite or moctezumite, which have similar forms and colors. Distinguishing them from each other is impossible without specialized laboratory tests. From other secondary minerals, such as goethite, it is distinguished by its distinct crystalline form. ## Crystal Forms It forms elongated, prismatic crystals with a hexagonal cross-section, often terminated by hexagonal pyramid faces. It occurs as single, isolated crystals or small groups in vugs and rock fissures.

Geological environment

## Genesis Ilirneyite is a secondary mineral, forming in the oxidation (weathering) zones of hydrothermal gold and tellurium deposits. It forms as a result of the alteration of primary tellurides under low temperature and pressure conditions, in the presence of oxygen and groundwater. ## Mineral Associations At the type locality, it co-occurs with quartz, barite, goethite, hematite, as well as other rare tellurites and tellurates, such as mackayite, poughite, emmonsite, zemannite, moctezumite, and other, yet undescribed mineral phases. ## Localities The only confirmed and described occurrence of ilirneyite in the world is its type locality: the Sentyabr’skoe deposit in the Ilirney ore district, Chukotka Autonomous Okrug, Far East Russia.

Rarity

Very rare

For collectors

## Quality Criteria The most highly prized ilirneyite specimens are those that contain well-formed, sharply terminated crystals with an intense, reddish-brown color and good luster. The size of the crystals is also important – specimens with crystals exceeding 0.5 mm are considered exceptional. Attractiveness is enhanced by a contrasting, light matrix (e.g., quartz) and the presence of other rare tellurium minerals. ## Popular Localities The only source of ilirneyite specimens is the Sentyabr’skoe deposit in Chukotka, Russia. Material from this locality is extremely rare on the collector's market and fetches high prices, even for microscopic specimens.

Care and storage

## Cleaning Ilirneyite specimens should be cleaned with utmost care, using only compressed air to remove dust. Due to its extreme rarity and potential solubility, contact with water and any chemical agents should be avoided. ## What to Avoid Ultrasonic cleaners, chemical agents, acids, and solvents must be absolutely avoided. The mineral may be sensitive to changes in temperature and humidity. It should not be exposed to direct sunlight. ## Storage Due to their microscopic size and fragility, ilirneyite specimens should be stored in specialized, sealed "micromount" boxes. This protects them from mechanical damage, dust, and sudden environmental changes.