Beryllosachanbińskiite-Na
Chemical formula: NaMn<sup>2+</sup><sub>4</sub>(Al<sub>5</sub>Be)(AlSi<sub>5</sub>O<sub>18</sub>)<sub>2</sub>·2H<sub>2</sub>O
Beryllosachanbinskite-Na is an extremely rare mineral from the beryl group, named after its discovery location and chemical composition.
Description
## Characteristics Beryllosachanbinskite-Na is a member of the beryl group and a sodium (Na) analogue of beryllosachanbinskite-Mg. It forms very small, slender, prismatic or acicular crystals, which typically occur as radial or sheaf-like aggregates. Individual crystals rarely exceed 1 mm in length and several tens of micrometers in thickness. It is a mineral typical for micromineralogical specimens. ## Physical Properties The hardness of the mineral is estimated at approximately 5 on the Mohs scale. It has a density of 2.89 g/cm³ (calculated value) and is characterized by a vitreous luster. It is transparent and does not exhibit pleochroism or luminescence under ultraviolet light. ## Colors and Varieties The mineral is colorless or has a very pale blue hue. No colored or commercial varieties are known. ## History and Name The name of the mineral refers to its chemical composition, in which sodium (Na) dominates and beryllium is present, and to its discovery location – the Sakhanbinskoe (Russian: Саханбинское) beryllium deposit in Siberia. It was officially recognized by the International Mineralogical Association (IMA) in 2020 (IMA2020-032). It was described by a research team led by Igor V. Pekov. ## Applications Due to its extreme rarity and microscopic crystal sizes, beryllosachanbinskite-Na has no practical applications. It is solely an object of scientific and collecting interest for specialized micromineral collectors.
Diagnostic features
## Identification Identification of beryllosachanbinskite-Na based on visual characteristics is impossible. Reliable identification requires advanced analytical techniques, such as chemical analysis using an electron microprobe (EDS/WDS) and X-ray diffraction (XRD). A key clue is the origin of the specimen from the only known locality. ## Distinguishing from similar minerals The mineral is visually indistinguishable from other members of the beryl group occurring in the same association, especially from pekovite, beryl, and its magnesium analogue, beryllosachanbinskite-Mg. Differences can only be determined by precise chemical analysis. ## Crystal forms Crystals are slender, prismatic with a hexagonal cross-section, often elongated and acicular. They usually form fan-shaped, radial, or chaotically arranged aggregates.
Geological environment
## Genesis Beryllosachanbinskite-Na forms under hydrothermal conditions, in fractures and small cavities within pegmatite veins cutting nepheline syenites. It is a product of crystallization from solutions rich in sodium, beryllium, and silica. ## Mineral associations This mineral coexists with a number of other rare minerals at its type locality. It is most commonly associated with tugtupite, sodalite, pekovite, chkalovite, albite, microcline, aegirine, natrolite, and beryllite. ## Localities The only confirmed occurrence of beryllosachanbinskite-Na in the world is the Sakhanbinskoe beryllium deposit, located within the Murun Massif in the Transbaikal Region of Siberia, Russia.
Rarity
Extremely rare
Collector aspects
## Quality criteria For such a rare micromineral, its collector's value is primarily determined by the richness of the specimen – the quantity and size of crystal aggregates on the rock matrix. Well-formed, radial aggregates with distinct, undamaged crystals are highly valued. The presence of rare associated minerals, such as tugtupite or pekovite, also enhances its attractiveness. ## Popular localities The only source of specimens is the type locality in Russia. Collector's material is extremely difficult to obtain and appears on the market very sporadically, mainly in specialized circles.
Care and storage
## Cleaning Specimens of this mineral are extremely small and fragile. Mechanical or chemical cleaning is not recommended and can easily damage the crystals. If necessary, a gentle stream of compressed air can be used to remove dust. ## What to avoid Avoid contact with any chemicals, ultrasonic cleaners, and sudden temperature changes. The mineral is susceptible to mechanical damage. ## Storage Specimens should be stored exclusively in specialized "micromount" boxes, protected from dust, shocks, and direct sunlight. Stable room conditions are entirely sufficient.