Smolyaninovite

Chemical formula: Co₂+₃Fe₃+₂(As₅+O₄)₄·₁₁H₂O

Smolyaninovite is a rare, hydrated cobalt and iron arsenate, forming microscopic, acicular crystals of a pinkish-violet color.

## Characteristics Smolyaninovite is a very rare secondary mineral from the arsenate group. It occurs as fine, radial or tangled aggregates, as well as crusts. Individual crystals are acicular or bladed and are extremely small, rarely exceeding 1 mm in length. Due to its chemical composition, it is closely related to erythrite (cobalt arsenate) and annabergite (nickel arsenate). ## Physical Properties Smolyaninovite crystals are characterized by a hardness of about 2 on the Mohs scale, which makes them very soft and brittle. They have a vitreous to pearly luster on cleavage surfaces. They are transparent to translucent. The mineral's density is approximately 3.13 g/cm³. ## Colors and Varieties The mineral exhibits colors from pinkish-violet and violet-pink to pale pink. No varieties have been distinguished. ## History and Name Smolyaninovite was first described in 1956 by L.K. Yakhontova. The mineral is named in honor of Nikolay Alekseevich Smolyaninov (1885–1957), a Russian mineralogist and deposit researcher from the Moscow Institute of Geological Research. ## Uses Smolyaninovite has no industrial application. It is solely of scientific and collectible importance as a very rare mineral.

Properties

Mohs hardness: 2
Luster: Vitreous
Streak: Light pink
Density: 3.13
Cleavage: Good on {010}
Fracture: Uneven
Transparency: Transparent to translucent
Crystal system: Orthorhombic

Diagnostic features

## Identification Smolyaninovite is identified by its characteristic pinkish-violet color, acicular crystal habit forming radial aggregates, and occurrence in the oxidation zones of cobalt and iron deposits. It is a very soft and brittle mineral. Final identification requires advanced analytical methods such as X-ray diffraction (XRD) or chemical analysis (EDS). ## Distinguishing from Similar Minerals Smolyaninovite can be confused with erythrite, which has a similar, though usually more intense, carmine-pink to violet color and also forms acicular crystals. However, erythrite does not contain iron. The differences between them are subtle and often require chemical analysis for definitive confirmation. ## Crystal Forms Crystals are elongated, acicular or bladed, often flattened. They typically form radial, stellate, or tangled aggregates, as well as thin crusts on the host rock.

Geological environment

## Genesis Smolyaninovite is a secondary mineral, formed in the oxidation (weathering) zones of hydrothermal ore deposits rich in arsenic, cobalt, and iron. It forms as a result of the weathering of cobalt and iron arsenides, such as skutterudite or safflorite. ## Mineral Associations This mineral co-occurs with other secondary arsenates, such as erythrite, annabergite, pharmacosiderite, scorodite, as well as goethite, quartz, and calcite. It also occurs in association with the primary ores from which it forms. ## Localities The most important and classic localities for smolyaninovite are the Bou Azzer deposit in Morocco and the Vostok-2 mine in the Almaty region of Kazakhstan (type locality). It is also known from several locations in Germany (Saxony, Black Forest) and from the nickel-cobalt mine in Spain.

Rarity

Very rare

For collectors

## Quality Criteria The quality of smolyaninovite specimens is primarily assessed based on the intensity and saturation of the pinkish-violet color. Specimens with well-formed, radial aggregates of acicular crystals, clearly contrasting with the host rock, are most valued. Due to the microscopic size of the crystals, the aesthetics of the entire aggregate and its contrast with the matrix are crucial. Specimens with rich, vividly colored crusts are also sought after. ## Popular Localities The best and most well-known smolyaninovite specimens available on the collector's market come from the Bou Azzer deposit in Morocco. Specimens from this locality are characterized by beautiful, radial aggregates with intense color.

Care and storage

## Cleaning Smolyaninovite specimens are extremely delicate and sensitive. Mechanical cleaning is not recommended. If absolutely necessary, compressed air can be used from a distance to remove loose dust. Avoid contact with water, which can damage or dissolve the mineral. ## What to Avoid Absolutely avoid contact with water and any chemicals. The mineral is very soft and brittle, so it must be protected from any impact, shock, or abrasion. It should not be heated or exposed to changes in humidity. ## Storage Smolyaninovite specimens should be stored in stable conditions, in closed, padded "micromount" boxes that protect them from mechanical damage, dust, and humidity changes. They should be kept away from vibrations and heat sources.

Sources

IMA Mineral List (CNMNC)