Strakhovite

Chemical formula: NaBa₃(Mn₂+,Mn₃+)₄[Si₄O₁₀(OH)₂][Si₂O₇]O₂·(F,OH)·H₂O

Strakhovite is a very rare, brown silicate mineral with a complex chemical composition, found in manganese deposits in Russia.

## Characteristics Strakhovite is a mineral with a brown to reddish-brown color and a dull or resinous luster. It occurs as fine-grained, dense aggregates or thin veins cutting through the rock. Due to its rarity and occurrence in small clusters, well-formed crystals are not known, and its appearance is usually inconspicuous. ## Physical Properties This mineral is characterized by a Mohs hardness of approximately 5. It is opaque, and its streak is light brown. The density of strakhovite has been calculated as 4.12 g/cm³. ## History and Name Strakhovite was named in honor of Nikolai Mikhailovich Strakhov (1900-1978), a Russian geologist and geochemist, member of the Russian Academy of Sciences. The mineral was approved by the IMA in 1995, and its discovery was first described in 1997. The type locality is the Severnyi manganese deposit in the Sverdlovsk Oblast in the Urals, Russia.

Properties

Mohs hardness: 5
Luster: Resinous
Streak: Light brown
Density: 4.12
Cleavage: Perfect on {001}
Fracture: Uneven
Transparency: Opaque
Crystal system: Monoclinic

Diagnostic features

## Identification Identifying strakhovite under collector conditions is practically impossible without advanced analytical methods. Its identification relies on chemical analysis (EDS) and X-ray diffraction (XRD). It is distinguished by its brown color, light brown streak, and occurrence in a specific geological environment. ## Differentiation from similar minerals It can be confused with other brown manganese minerals with which it co-occurs, such as piedmontite, braunite, or hausmannite. Definitive differentiation requires specialized laboratory equipment to determine its chemical composition and crystal structure. ## Crystal forms Strakhovite forms dense, fine-grained aggregates and thin veins up to 1 cm thick. Well-formed crystals visible to the naked eye have not been observed.

Geological environment

## Genesis Strakhovite forms as a result of metamorphic processes within manganese deposits. It occurs in veins cutting through rocks composed of other manganese minerals, such as piedmontite and braunite. ## Mineral associations This mineral co-occurs with piedmontite, braunite, manganite, hausmannite, todorokite, cryptomelane, as well as quartz and calcite. ## Localities The only confirmed locality for strakhovite in the world is its type locality – the Severnyi manganese deposit, located in the Ivdel district of the Sverdlovsk Oblast in the Northern Urals, Russia.

Rarity

Extremely rare

For collectors

## Quality criteria Due to its extreme rarity, every analytically confirmed strakhovite specimen is valuable for specialized systematic collections and scientific institutions. The most highly prized specimens will be those where strakhovite is clearly visible, forms the richest possible clusters, and is well-contrasted with the surrounding rock matrix. The presence of associated minerals can increase the documentary value of the specimen. ## Popular localities The only source of specimens is the Severnyi deposit in the Urals, Russia, which makes them extremely difficult to acquire on the collector's market.

Care and storage

## Cleaning Due to its extreme rarity and occurrence as small aggregates on a rock matrix, mechanical cleaning is not recommended. Any contaminants can be removed very carefully with a soft-bristled brush. Contact with water and chemical agents should be avoided. ## What to avoid Contact with acids and other chemicals that could damage the mineral must be absolutely avoided. It should not be subjected to ultrasound or sudden temperature changes. Specimens should be protected from moisture and direct sunlight, which could theoretically affect its color. ## Storage Strakhovite specimens, being extremely rare, should be stored under stable conditions, preferably in a closed display box away from dust and light. Storage in a dry place is recommended to avoid potential chemical reactions with airborne moisture.

Sources

IMA Mineral List (CNMNC)