Bario-olgite

Chemical formula: Na(Na,Sr,Ce<sup>3+</sup>)<sub>2</sub>Ba(PO<sub>4</sub>)<sub>2</sub>

Bario-olgite is a rare sodium, barium, and strontium phosphate, a barium analogue of olgite, forming small, blue-green crystals.

## Characteristics Bario-olgite is a rare mineral belonging to the phosphate group, chemically related to belovite and olgite. It forms small, tabular or short-prismatic crystals, rarely exceeding a few millimeters. Most often, it occurs as fine, granular aggregates embedded in the host rock. Its most characteristic feature is its attractive, light color. ## Physical Properties This mineral is relatively soft, with a Mohs hardness of 4.5. It has a vitreous luster and is transparent. Its density is quite high, approximately 4.13 g/cm³. ## Colors and Varieties Bario-olgite occurs in shades from light blue to blue-green. Its color is one of the main features allowing for preliminary identification. No commercial or colored varieties are distinguished. ## History and Name The mineral was first described in 1981 by Alexander P. Khomyakov, E. I. Semenov, and others. Its name refers to its chemical composition – the dominance of barium ("bario") – and its structural similarity to olgite. Olgite, in turn, was named after the Russian geologist Olga Anisimovna-Vorobieva. ## Applications Due to its extreme rarity and small crystal size, bario-olgite has no industrial applications. It is solely an object of scientific and collecting interest.

Properties

Mohs hardness
4.5
Luster
Vitreous
Streak
White
Density
4.13
Cleavage
Good on {0001}
Transparency
Transparent
Crystal system
Trigonal

Diagnostic features

## Identification Key diagnostic features of bario-olgite include its characteristic blue-green color, vitreous luster, and occurrence in a specific geological environment – alkaline pegmatites. Good cleavage in one direction can also be helpful in identification. ## Distinguishing from Similar Minerals Bario-olgite can be confused with other blue or green minerals from the same locality, especially with the related olgite. Distinguishing these two minerals based on visual characteristics is practically impossible and requires advanced chemical analyses (e.g., EDS) to confirm the dominance of barium over strontium. ## Crystal Forms Bario-olgite crystals have a trigonal habit, most often in the form of hexagonal tablets or short prisms. They are usually small and occur as single crystals or granular aggregates in the rock.

Geological environment

## Genesis Bario-olgite is an igneous mineral, crystallizing in the late stages of the evolution of nepheline-syenite pegmatites. It forms in a strongly alkaline environment, rich in sodium, barium, and rare earth elements. ## Mineral Associations This mineral occurs in association with other rare alkaline minerals. Its most common associations include aegirine, analcime, fluorapatite, lorenzenite, microcline, nepheline, sodalite, ussingite, and vuonnemite. ## Localities The only significant and classic occurrence of bario-olgite in the world is its type locality – Mount Karnasurt in the Lovozero Massif on the Kola Peninsula in Russia. This is one of the world's most famous sites for rare alkaline minerals.

Rarity

Very rare

For collectors

## Quality Criteria The quality of bario-olgite specimens is primarily judged by the intensity and purity of color, the size and degree of crystal development, and their transparency. The most valued are well-formed, blue-green crystals embedded in a contrasting rock matrix, often in association with other rare minerals from the Lovozero Massif. ## Popular Localities For collectors, the only source of bario-olgite specimens is the Lovozero Massif on the Kola Peninsula in Russia. Specimens from this locality are the standard for this mineral and a reference point for the entire global supply.

Care and storage

## Cleaning Bario-olgite specimens should be cleaned very carefully, using a soft brush and distilled water. Due to its moderate hardness, it is easily scratched. Ultrasonic cleaners, which can damage the crystals, should be avoided. ## What to Avoid This mineral is sensitive to acids. Contact with household and laboratory chemicals should be avoided. It should also be protected from impacts and sudden temperature changes. ## Storage Collector's specimens of bario-olgite are best stored in separate, padded boxes to prevent abrasion and scratching by harder minerals. Protect from dust and moisture.

Sources

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