Tuliokite

Chemical formula: Na₆BaTh⁴⁺(CO₃)₆·6H₂O

Tuliokite is a rare, complex sodium, barium, and thorium carbonate, forming colorless or white, pseudohexagonal crystals with a vitreous luster.

## Characteristics Tuliokite is a complex, hydrated sodium, barium, and thorium carbonate. This mineral forms characteristic, tabular or prismatic crystals, which often exhibit a pseudohexagonal outline, even though they actually crystallize in the triclinic system. It usually occurs as small, well-formed crystals, reaching up to 2-3 mm, or in the form of radial aggregates. It is colorless to white, and its surfaces are characterized by a vitreous luster. ## Physical Properties This mineral is relatively soft, with a hardness of about 3 on the Mohs scale. It is transparent to translucent. Its density is quite high, approximately 3.1 g/cm³, which is a result of the presence of heavy elements such as barium and thorium. Tuliokite is radioactive due to its thorium content. ## Colors and Varieties Tuliokite is usually colorless or white. Some specimens may have a pale yellow tint. No color or commercial varieties are distinguished. ## History and Name The mineral's name comes from the Tuliok River (Russian: Тульйок), near which the Khibiny Massif on the Kola Peninsula in Russia is located, where it was first found. Tuliokite was described and approved as a new mineral by the International Mineralogical Association (IMA) in 1989. Its discoverers are Russian mineralogists A.P. Khomyakov, L.I. Polezhaeva, G.N. Nechelyustov, and I.M. Marsiy. ## Uses Due to its rarity, small crystal size, and radioactivity, tuliokite has no industrial application. It is solely an object of interest for collectors specializing in rare minerals, especially those originating from the alkaline massifs of the Kola Peninsula.

Properties

Mohs hardness
3-4
Color
Colourless, white
Luster
Vitreous
Streak
White
Density
3.15
Cleavage
Perfect on {001}
Fracture
Conchoidal
Transparency
Transparent,Translucent
Crystal system
Trigonal

Diagnostic features

## Identification Characteristic features of tuliokite include its pseudohexagonal, tabular crystals, vitreous luster, and occurrence in a specific geological environment – ultra-alkaline pegmatites. It reacts with acids, releasing carbon dioxide. Its radioactivity is a key diagnostic feature, easily detectable with a Geiger counter. ## Distinguishing from similar minerals Tuliokite can be confused with other colorless carbonates found in the same environment, such as burbankite or shortite. However, its unique chemical composition (presence of thorium and barium), which can be confirmed by chemical analysis (EDS/WDS), distinguishes it. Its pseudohexagonal habit and radioactivity are also helpful in differentiating it from other associating minerals. ## Crystal forms Tuliokite crystals are usually tabular, with a hexagonal outline, which is a result of twinning. They occur as single, well-formed crystals or form radial and fan-shaped aggregates.

Geological environment

## Genesis Tuliokite is a hydrothermal mineral, crystallizing in the late stages of the evolution of highly differentiated alkaline complexes. It forms in voids and fractures in natrolite-ussingite pegmatites, which cut foyaite and rischorrite. ## Mineral associations This mineral co-occurs with a wide range of other rare alkaline minerals. The most common associations include: ussingite, natrolite, shortite, trona, thermonatrite, burbankite, khomyakovite, sidorenkite, as well as aegirine, microcline, and lorenzenite. ## Localities The most important and type locality for tuliokite is the Khibiny Massif on the Kola Peninsula in Russia, specifically the Koashva and Rasvumchorr mountains. It is also known from another alkaline massif in this region – Lovozero (including Mount Alluaiv). These are the only confirmed localities of this mineral worldwide.

Rarity

Very rare

For collectors

## Quality criteria The most prized specimens by collectors are those with sharp, well-formed, pseudohexagonal crystals that are transparent and free from damage. The attractiveness of a specimen is enhanced by a contrasting background, such as dark host rock or association with colorful minerals. Crystal size is crucial – specimens exceeding a few millimeters are rare. Rich radial aggregates are also highly valued. ## Popular localities By far the most sought-after specimens come from the type locality in the Khibiny Massif on the Kola Peninsula in Russia. Specimens from the Koashva and Rasvumchorr mountains are considered classic for this mineral.

Care and storage

## Cleaning Tuliokite specimens should be cleaned very carefully, using a soft brush to remove dust. Due to its water solubility, contact with water should be avoided. If wet cleaning is necessary, use alcohol (e.g., ethanol) and immediately dry the specimen. ## What to avoid Contact with water and acids, which can damage or dissolve the mineral, must be strictly avoided. Tuliokite is brittle and susceptible to mechanical damage. As a radioactive mineral, it requires careful handling – avoid inhaling dust and wash hands after each contact. ## Storage Specimens should be stored in a dry place, preferably in a sealed, lidded display box, to protect them from moisture and mechanical damage. Due to its radioactivity, it should not be stored in places of permanent human presence, such as bedrooms or desks. It is recommended to keep it in a dedicated display case or box, away from other radiation-sensitive minerals.

External references

Sources

Read more