Beryllocordierite-Na

Chemical formula: NaMg₄(Al₅Be)(AlSi₅O₁₈)₂·₂H₂O

Beryllocordierite-Na is an extremely rare, blue mineral from the cordierite group, being a hydrated beryllium silicate of sodium, magnesium, and aluminum.

## Characteristics Beryllocordierite-Na is a member of the sekaninaite supergroup and the cordierite group. It occurs as very fine, anhedral (irregularly shaped) grains up to 0.1 mm in size, forming aggregates within the host rock. Due to their size, the visual characteristics of individual crystals are difficult to observe without specialized equipment. ## Physical properties The mineral is characterized by a vitreous luster and is transparent. Its Mohs hardness is approximately 8, which is a high value, typical for minerals of this group. The density calculated based on the chemical formula and unit cell parameters is 2.55 g/cm³. ## Colors and varieties Observed specimens are pale blue. The streak of the mineral is white. No varieties have been distinguished. ## History and name The mineral's name refers to its chemical composition – it is a cordierite analog containing beryllium (Beryllo) and sodium (Na). It was approved as a new mineral by the International Mineralogical Association (IMA) in 2016 under number IMA2016-057. The type locality where it was discovered is Mount Koashva on the Kola Peninsula in Russia.

Properties

Mohs hardness: 8
Luster: Vitreous
Streak: White
Density: 2.55
Cleavage: Good on {100}, poor on {010} and {001}
Fracture: Uneven
Transparency: Transparent
Crystal system: Orthorhombic

Diagnostic features

## Identification Identification of Beryllocordierite-Na is impossible without advanced analytical techniques. It requires chemical analysis (e.g., using an electron microprobe - EDS/WDS) to confirm the presence of sodium, magnesium, aluminum, beryllium, and silicon in appropriate proportions, as well as X-ray diffraction (XRD) methods to determine the crystal structure. ## Distinction from similar minerals It is distinguished from other minerals of the cordierite group (such as cordierite or sekaninaite) by its unique chemical composition, particularly the simultaneous presence of beryllium and sodium as dominant elements in their structural positions. Visually, it is indistinguishable from many other blue minerals occurring in similar parageneses. ## Crystal forms The mineral forms anhedral, i.e., irregularly shaped, grains up to 100 micrometers in size.

Geological environment

## Genesis Beryllocordierite-Na forms under conditions of contact metamorphism. At the type locality (Mount Koashva), it occurs in xenoliths (fragments of foreign rock) of metasediments that were incorporated into an intrusion of alkaline igneous rocks (urtites) and subjected to high temperatures. ## Mineral associations This mineral coexists with minerals such as donpeacorite, sekaninaite, indialite, enstatite, andalusite, sillimanite, quartz, plagioclase, anorthite, clinochlore, phlogopite, dravite, and pyrite. ## Localities The only confirmed locality of Beryllocordierite-Na in the world is Mount Koashva, Khibiny Massif, Kola Peninsula, Murmansk Oblast, Russia.

Rarity

Extremely rare

For collectors

## Quality criteria As a microscopic mineral, Beryllocordierite-Na is not evaluated based on typical collector criteria such as size, color, or visual clarity. The scientific and collector value of a specimen lies in its confirmed identity, the richness of aggregates in the host rock, and the presence of interesting associated minerals. Specimens are significant only for specialized micromineral collections and scientific institutions. ## Popular localities The only source of specimens is its type locality - Mount Koashva in Russia.

Care and storage

## Cleaning Due to its extreme rarity and occurrence as microscopic grains embedded in rock, specimens are not subject to cleaning by collectors. In laboratory conditions, standard procedures for electron microprobe analysis are applied. ## What to avoid All aggressive chemicals, ultrasonics, and extreme temperature changes should be avoided. Specimens should be treated solely as research material. ## Storage Specimens should be stored under stable conditions, in specialized micromineral containers, away from dust and contaminants, and protected from mechanical damage.

Sources

IMA Mineral List (CNMNC)