Rudashevskyite

Chemical formula: (Fe₂+,Zn₂+)S₂-

Rudashevskyite is an extremely rare iron-zinc sulfide, closely related to sphalerite, found in meteorites.

## Characteristics Rudashevskyite is a sulfide group mineral, representing the natural iron-zinc sulfide with a sphalerite structure. It has been identified as microscopic, rounded grains up to 200 micrometers in size, embedded in other minerals. Its appearance in reflected light is gray, with a brownish tint. ## Physical Properties Due to the microscopic size of the grains, most physical properties, such as hardness, density, or luster, have not been precisely determined. The mineral is opaque. ## Colors and Varieties The mineral has a gray color with a brownish tint. No varieties have been distinguished. ## History and Name The mineral is named in honor of Prof. Dr. Nikolai Sergeevich Rudashevsky (born 1940), a Russian mineralogist from St. Petersburg, a specialist in the mineralogy of ore minerals and meteorites. Rudashevskyite was approved as a new mineral by the International Mineralogical Association (IMA) in 2006 (IMA2006-004). It was described based on findings in two iron meteorites: Dronino (Russia) and Muonionalusta (Sweden). ## Applications Due to its extreme rarity and microscopic size, rudashevskyite has no practical applications. It is solely an object of scientific and collecting interest in the context of meteorite mineralogy.

Properties

Luster: Metallic
Transparency: Opaque
Crystal system: Cubic

Diagnostic features

## Identification Identification of rudashevskyite is possible only through advanced laboratory methods, such as chemical composition analysis using an electron microprobe (EDS/WDS) and X-ray diffraction (XRD). In reflected light under a microscope, it is gray with a brownish tint and exhibits weak anisotropy. ## Distinguishing from Similar Minerals It can be confused with other sulfides found in meteorites, such as troilite, daubréelite, or sphalerite. From sphalerite, with which it is structurally identical, it differs by the dominance of iron over zinc. Precise differentiation requires chemical analysis. ## Crystal Forms It occurs as irregular, rounded, or xenomorphic (anhedral) grains and intergrowth aggregates within other minerals, mainly kamacite.

Geological environment

## Genesis Rudashevskyite is a mineral of extraterrestrial origin. It forms in iron meteorites (octahedrites), likely as a result of processes occurring within the parent body of an asteroid. It forms under strongly reducing conditions, with low sulfur fugacity. ## Mineral Associations It co-occurs with other minerals typical of iron meteorites, such as kamacite, taenite, troilite, daubréelite, chromite, graphite, and silicates (e.g., plagioclase). ## Localities Its occurrence has been confirmed to date in two iron meteorites: - **Dronino**, found in the Ryazan Oblast, Russia (type locality). - **Muonionalusta**, found in the Pajala Municipality, Sweden.

Rarity

Extremely rare

For collectors

## Quality Criteria The quality of a rudashevskyite specimen is identical to the quality of the meteorite itself in which the mineral is found. For collectors specializing in mineral systematics or meteorite mineralogy, any scientifically confirmed specimen has value. The most valuable are polished sections or slices of meteorites where rudashevskyite has been identified and is visible in association with other rare mineral phases. ## Popular Localities Both known localities – the Dronino and Muonionalusta meteorites – are sources of specimens. Fragments of these meteorites are available on the collector's market, but only a small portion of them contain confirmed occurrences of rudashevskyite.

Care and storage

## Cleaning Specimens (usually meteorite fragments) containing rudashevskyite should not be wet-cleaned. Dust can be removed with a soft brush or compressed air. ## What to Avoid All chemicals, water, and ultrasonics are inadvisable. The mineral, as a sulfide, is susceptible to oxidation, especially in a humid environment. High temperatures and sudden temperature changes should be avoided. ## Storage Store in stable conditions, in a dry environment, preferably in an airtight container (e.g., a "membrane box") with a desiccant. Protect from direct sunlight and dust.

Sources

IMA Mineral List (CNMNC)