Kuvaevite

Chemical formula: Ir₅Ni₁₀S₁₆

Kuvaevite is a very rare iridium and nickel sulfide, occurring as fine, metallic grains in ultramafic geological complexes.

## Characteristics Kuvaevite is an iridium and nickel sulfide, belonging to the mineral group named after it. It occurs as very small, irregular grains, usually not exceeding a few tens of micrometers in size. Due to its size and mode of occurrence, its visual characteristics are difficult to observe without specialized equipment, such as an electron microscope. In reflected light, it exhibits a metallic appearance. ## Physical Properties This mineral is opaque and characterized by a metallic luster. Its density, calculated based on the chemical formula and unit cell parameters, is 6.37 g/cm³. Other physical properties, such as hardness, have not yet been determined due to the very small size of the grains. ## Colors and Varieties Kuvaevite is gray to grayish-brown in color. No varieties have been distinguished. ## History and Name The mineral's name honors the Russian mineralogist and geochemist, Dr. Nikolay Nikolaevich Kuvaev (born 1952), for his contributions to the study of platinum-group minerals in Siberian ultramafic massifs. Kuvaevite was approved as a new mineral species by the International Mineralogical Association (IMA) in 2018 (IMA2018-058). It was discovered and described by a team of researchers, including A. Y. Barkov and M. A. Yudovskaya.

Properties

Luster
Metallic
Density
6.37
Transparency
Opaque
Crystal system
Trigonal

Diagnostic features

## Identification Identification of kuvaevite is impossible without advanced laboratory techniques. It requires the use of a scanning electron microscope (SEM) equipped with an energy-dispersive spectrometer (EDS) or a wavelength-dispersive spectrometer (WDS) for precise chemical composition analysis. Confirmation of the crystal structure is obtained using electron diffraction. ## Distinguishing from Similar Minerals Kuvaevite is visually indistinguishable from many other platinum-group metal sulfides, such as cuproiridsite, malanite, or other minerals from the kuvaevite group. The only way to differentiate them is through detailed quantitative chemical analysis and crystal structure investigation. ## Crystal Forms This mineral forms exclusively anhedral (irregular) grains and aggregates, often intergrown with other sulfides. It has not been observed in the form of well-developed crystals.

Geological environment

## Genesis Kuvaevite forms as a result of magmatic processes within differentiated ultramafic complexes, consisting of dunites, peridotites, and gabbros. It crystallizes from late, sulfur- and platinum-group element-rich residual melts that segregated from the main magma. Its formation is associated with the concentration of iridium and nickel under specific physicochemical conditions. ## Mineral Associations This mineral co-occurs with other platinum-group minerals (PGM), such as laurite, cuproiridsite, irarsite, as well as with base metal sulfides like pentlandite, chalcopyrite, and heazlewoodite. It also appears in association with chromite and serpentine group minerals. ## Localities The only confirmed locality of kuvaevite in the world (type locality) is the gold-bearing zone of the Sisim River within the Lysan dunite-peridotite-gabbro complex, located in the Krasnoyarsk Krai, Siberia, Russia.

Rarity

Extremely rare

For collectors

## Quality Criteria Kuvaevite is not a collector's mineral in the traditional sense. Its value is purely scientific and research-oriented. Specimens typically consist of rock fragments or polished sections intended for microscopic analysis. The only criterion for "quality" is the confirmed presence of the mineral and its abundance in a given fragment, which allows for further research.

Care and storage

## Cleaning Due to the extremely small size of the grains and their occurrence within the host rock, kuvaevite specimens are not cleaned in the traditional sense. All analyses and surface cleaning are performed under laboratory conditions using specialized techniques, such as focused ion beam. ## What to Avoid Specimens containing kuvaevite should be protected from aggressive chemicals that could react with sulfides or the surrounding rock. Ultrasonic cleaners and sudden temperature changes should be avoided. ## Storage Storage should be in stable, dry conditions, away from dust and contaminants. It is best to keep them in specialized micromount boxes or sealed containers to prevent mechanical damage and oxidation.

External references

Sources

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