Bazhenovite

Chemical formula: Ca₈(S₅)₂-(S₆+O₃S₂-)(OH)₁₂·₂₀H₂O

Bazhenovite is an extremely rare, pale yellow calcium sulfate-sulfide mineral, forming microscopic, acicular crystals.

## Characteristics Bazhenovite is a complex, hydrated calcium sulfate and sulfide, occurring as extremely small, acicular or bladed crystals. It typically forms radial aggregates, rosettes, or tangled, felt-like masses. Individual crystals rarely exceed 0.5 mm in length and are too small to be observed with the naked eye. The mineral is characterized by a pale yellow, canary-yellow color. ## Physical Properties Bazhenovite crystals are flexible and pliable. Due to the microscopic size of the crystals, hardness and density have not been precisely measured. The luster is described as silky, which is typical for fibrous aggregates. It is a transparent mineral. ## Colors and Varieties This mineral occurs in a uniform, pale yellow or canary-yellow color. No varieties have been distinguished. ## History and Name Bazhenovite was discovered in the Kopeisk lignite mine in the Chelyabinsk Oblast, Southern Urals, Russia. It was described and approved as a new mineral by the International Mineralogical Association (IMA) in 1995. Its name honors the Russian geologist and mineralogist Alexander G. Bazhenov (1917–1995), a researcher of the geology of the Urals. ## Uses Bazhenovite has no industrial application and is solely an object of scientific interest and a collector's item for specialized collectors of rare minerals.

Properties

Luster: Silky
Streak: Light yellow
Cleavage: Perfect on {100}
Fracture: Uneven
Transparency: Transparent
Crystal system: Monoclinic

Diagnostic features

## Identification Identification of bazhenovite is based on its unique appearance and occurrence environment. Characteristic features include its pale yellow color, silky luster, and the form of small, acicular crystals forming radial or felt-like aggregates. It occurs on burning mine dumps. ## Distinguishing from Similar Minerals It can be confused with other secondary sulfates and sulfides formed under similar conditions, such as various sulfur compounds. Final identification requires advanced analytical methods, such as X-ray diffraction (XRD) or chemical microanalysis (EDS), due to the microscopic size of the crystals. ## Crystal Forms Bazhenovite forms very fine, elongated crystals with an acicular or bladed habit. These crystals combine into characteristic radial aggregates, rosettes, and dense, tangled clusters resembling felt.

Geological environment

## Genesis Bazhenovite is a secondary mineral with a very specific genesis. It forms as a result of spontaneous combustion and burning of lignite on mine dumps. It develops in zones with temperatures ranging from 50 to 75°C, where hot sulfur-rich gases react with clay rocks containing calcite. ## Mineral Associations This mineral co-occurs with other rare minerals formed under the same conditions, such as native sulfur, gypsum, calcite, and other complex sulfates and sulfides. ## Localities The only confirmed locality of bazhenovite in the world is its type locality – the burning lignite mine dumps in Kopeisk, in the Chelyabinsk Basin, Southern Urals, Russia.

Rarity

Extremely rare

For collectors

## Quality Criteria The quality of bazhenovite specimens is assessed based on the richness and aesthetics of the crystal aggregates on the rock matrix. Specimens with well-formed, radially arranged rosettes of intense, pale yellow color are most highly valued. Due to the microscopic nature of the mineral, specimens are evaluated under magnification. ## Popular Localities The only source of bazhenovite specimens is its discovery site in Russia. Collector material from this locality is extremely limited and rarely available on the market.

Care and storage

## Cleaning Bazhenovite specimens are extremely delicate and sensitive. They should not be cleaned mechanically or chemically. Any attempts at cleaning, even with water, can destroy the microscopic crystals. It is best to leave the specimen undisturbed. ## What to Avoid Contact with water, chemicals, as well as any vibrations and impacts, must be strictly avoided. The mineral is unstable in contact with air – it undergoes slow decomposition. It should be protected from changes in temperature and humidity. ## Storage Bazhenovite specimens must be stored in tightly sealed, stable containers, preferably of the "micromount" type, to minimize contact with air and protect against mechanical damage. Storage in a dry environment is crucial for preserving the mineral's integrity.

Sources

IMA Mineral List (CNMNC)