Shenzhuangite

Chemical formula: Ni²⁺Fe²⁺S²⁻₂

Shenzhuangite is a rare nickel-iron sulfide, isostructural with pyrite, found mainly in iron meteorites.

## Characteristics Shenzhuangite is a very rare sulfide mineral, analogous to pyrite (FeS₂) with partial substitution of iron by nickel. It forms small, most often anhedral (irregular) grains with a metallic luster, usually embedded in the matrix of other meteoritic minerals. Its identification is almost exclusively possible using advanced analytical methods, such as electron microprobe analysis, due to its small size and similarity to other sulfides. ## Physical Properties This mineral is characterized by a metallic luster and black color. It is opaque. Due to its occurrence as very small grains, determining many physical properties, such as hardness or density, is difficult and has not been precisely performed on natural material. ## History and Name Shenzhuangite was officially recognized by the International Mineralogical Association (IMA) in 2007 (IMA2007-026). The name honors Shen-Suan Sun (1943–2003), a geochemist from Geoscience Australia, for his contributions to isotopic geochemistry and meteorites. The mineral was discovered in the Qingzhen (EH3) iron meteorite, which fell in China.

Properties

Luster
Metallic
Streak
Black
Cleavage
None
Fracture
Uneven
Transparency
Opaque
Crystal system
Tetragonal

Diagnostic features

## Identification Practical identification of shenzhuangite is impossible without specialized equipment. In laboratory studies, it is recognized based on its chemical composition (presence of nickel, iron, and sulfur in appropriate proportions) and crystallographic data obtained by X-ray diffraction. Optically, it is indistinguishable from other fine, metallic sulfides. ## Distinguishing from Similar Minerals It can be confused with pyrite, bravoite, troilite, or pentlandite, which often coexist in meteorites. Differentiation requires chemical composition analysis (EDS/WDS), as optical properties in reflected light are very similar. ## Crystal Forms Shenzhuangite occurs as very small, anhedral grains, usually not exceeding a few tens of micrometers in size. Well-formed crystals have not been observed.

Geological environment

## Genesis Shenzhuangite is a mineral of extraterrestrial origin. It forms under reducing conditions within the parent bodies of asteroids from which meteorites originate. Its presence has been confirmed in iron meteorites (octahedrites) and enstatite chondrites. ## Mineral Associations This mineral coexists with other minerals typical of meteorites, such as kamacite, taenite, troilite, schreibersite, perryite, niningerite, and silicates (enstatite, forsterite). ## Localities Confirmed occurrences of shenzhuangite are limited to a few meteorites. Besides the type locality – the Qingzhen meteorite (Guizhou province, China) – it has also been identified in the North Chile (Filomena) iron meteorite found in Chile and in the Adzhi-Bogdo (fall mass) enstatite chondrite found in the Gobi Desert in Mongolia.

Rarity

Extremely rare

For collectors

## Quality Criteria Shenzhuangite does not occur as standalone collector specimens. Its value is purely scientific, and it is merely a microscopic component of rare meteorite types. For a meteorite collector, the entire specimen (meteorite) holds value, and the presence of such a rare mineral as shenzhuangite, confirmed by research, significantly increases its scientific and potentially market value.

Care and storage

## Cleaning Specimens containing shenzhuangite, most often meteorite fragments, should not be wet cleaned. Dust can be gently removed using compressed air or a very soft brush. ## What to Avoid Contact with water, chemicals, and high humidity must be strictly avoided, as sulfides (including shenzhuangite and associated troilite) can oxidize, leading to specimen degradation. Sudden temperature changes should also be avoided. ## Storage Meteorite fragments containing this mineral should be stored under stable conditions, preferably in sealed, airtight containers (e.g., "membrane box" type) with a desiccant (silica gel). Exposure should be away from direct sunlight and heat sources.

External references

Sources

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