Nataliyamalikite

Chemical formula: Tl<sup>1+</sup>I<sup>1-</sup>

Thallium(I) iodide, an extremely rare fumarolic mineral with an intense reddish-orange color and adamantine luster.

## Characteristics Nataliyamalikite is a naturally occurring thallium(I) iodide. It forms efflorescences, thin coatings, and very small, isometric crystals, rarely exceeding several tens of micrometers in size. Its most characteristic feature is its intense, vivid color, ranging from reddish-orange to yellow. The mineral exhibits a strong, almost adamantine luster, which, combined with its vibrant color, makes it visually distinctive despite its microscopic size. ## Physical Properties It is a very soft mineral, with a Mohs hardness estimated at 1-2. Despite its softness, it has a very high density (7.07 g/cm³), resulting from the presence of heavy elements – thallium and iodine. It is translucent, and in thicker aggregates, opaque. It exhibits perfect cleavage. ## Colors and Varieties The mineral occurs in shades from orange to reddish-orange and yellow. No color or commercial varieties have been distinguished. ## History and Name Nataliyamalikite was officially recognized by the International Mineralogical Association (IMA) in 2020. Its name honors Nataliya Vladimirovna Malik, a Russian mineralogist and geochemist from the Institute of Volcanology and Seismology in Petropavlovsk-Kamchatsky, for her contributions to the study of fumarolic minerals. The type locality and only known occurrence is Avacha Volcano in Kamchatka, Russia. ## Applications Due to its extreme rarity, microscopic specimen sizes, and high toxicity of thallium, nataliyamalikite has no industrial applications. It is solely an object of scientific research and interest for specialized micromount mineral collectors.

Properties

Mohs hardness
1-2
Luster
Adamantine to resinous
Streak
Yellow
Density
7.07
Cleavage
Perfect on {100}
Fracture
Uneven
Transparency
Translucent to opaque
Crystal system
Cubic

Diagnostic features

## Identification Key diagnostic features include its occurrence environment (active volcanic fumaroles), intense reddish-orange color, adamantine luster, very high density, and extreme softness. Reaction to iodine and thallium in chemical tests is conclusive. ## Distinguishing from Similar Minerals It can be confused with other brightly colored volcanic sublimation products, such as native sulfur (much lighter, different odor), or lafossaite (different chemical composition and crystallographic system). It differs from sulfur by its much higher density and luster. Identification without advanced analytical methods (EDS, XRD) is very difficult. ## Crystal Forms It forms isometric, cubic crystals, often with a skeletal structure. It occurs mainly as thin coatings and efflorescences on volcanic rocks.

Geological environment

## Genesis Nataliyamalikite is a typical fumarolic mineral. It forms as a result of direct sublimation (resublimation) of hot volcanic gases rich in thallium and iodine. It crystallizes in zones with a relatively low temperature, around 100-120°C. ## Mineral Associations It co-occurs with other minerals formed under similar conditions, primarily native sulfur and other rare thallium halides, such as lafossaite. ## Localities The only confirmed and described occurrence in the world is the fumaroles of Avacha Volcano on the Kamchatka Peninsula in Russia.

Rarity

Extremely rare

For collectors

## Quality Criteria The quality of collector specimens (micromounts only) is assessed based on the richness of the efflorescence, the size and development of microcrystals, and the aesthetic composition with other associated minerals. Specimens with clearly visible, well-formed cubic crystals on a contrasting matrix are most valued. ## Popular Localities All collector and research material comes from a single location in the world – Avacha Volcano in Kamchatka.

Care and storage

## Cleaning Nataliyamalikite specimens are extremely delicate and small. Cleaning is generally not recommended. If necessary, only compressed air from a safe distance or a very soft, dry brush can be used to remove loose dust particles. Absolutely avoid water and any chemical agents. ## What to Avoid The mineral is very toxic due to its high thallium content. Avoid direct skin contact, inhalation of dust, and any possibility of ingestion. Always wash hands after contact with the mineral or the container in which it is stored. It should be protected from moisture, acids, high temperatures, and prolonged exposure to sunlight. ## Storage It should be stored in a tightly sealed, clearly labeled container (preferably with a toxicity warning label). The container should be kept in a dry place, away from children, pets, and living areas.

External references

Sources

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