Andreyivanovite

Chemical formula: FeCrP

Andreyivanovite is an iron and chromium phosphide, discovered in the Kaidun meteorite, distinguished by its extreme rarity and metallic luster.

## Characteristics Andreyivanovite is a mineral from the phosphide group, identified based on microscopic grains. Its typical specimens are irregular inclusions, not exceeding several tens of micrometers in size, occurring within other meteoritic minerals. Due to its size, visual characteristics visible to the naked eye cannot be determined. Under a microscope in reflected light, it presents a metallic appearance. ## Physical Properties This mineral is characterized by a strong metallic luster. It is opaque. Hardness and density have not been precisely measured due to the microscopic size of the grains; however, hardness is estimated based on similar synthetic phosphides. ## Colors and Varieties Observed in reflected light, it has a creamy-white color with a reddish tint. It does not exhibit pleochroism. No varieties are known. ## History and Name Andreyivanovite was officially recognized by the International Mineralogical Association (IMA) in 2006 (IMA2006-032). The name honors Andrei Valerievich Ivanov (born 1937), a Russian geochemist and meteorite researcher from the Vernadsky Institute of Geochemistry and Analytical Chemistry in Moscow, for his contribution to the study of the Kaidun meteorite, in which this mineral was discovered. ## Uses Andreyivanovite has no commercial or industrial applications. Its significance is purely scientific, serving as an indicator of processes occurring in the early Solar System.

Properties

Mohs hardness
6-7
Luster
Metallic
Transparency
Opaque
Crystal system
Tetragonal

Diagnostic features

## Identification Identification of andreyivanovite is possible only through advanced laboratory techniques, such as reflected light microscopy and X-ray microanalysis (EDS/WDS) to determine its chemical composition (presence of iron, chromium, and phosphorus in appropriate proportions). Its optical properties, such as a creamy-white color with a pinkish tint, are helpful. ## Distinguishing from Similar Minerals It can be confused with other metallic phosphides found in meteorites, such as schreibersite ((Fe,Ni)₃P) or allabogdanite ((Fe,Ni)₂P). Definitive differentiation requires precise chemical analysis, especially checking for the presence and ratio of chromium to iron. ## Crystal Forms Andreyivanovite occurs as anhedral (irregular) grains ranging from 5 to 30 micrometers in size. No well-formed crystal faces have been observed.

Geological environment

## Genesis Andreyivanovite is an extraterrestrial mineral. It formed under highly reducing conditions, with very low oxygen fugacity, which is characteristic of certain environments where matter formed in the Solar System. Its presence in the Kaidun meteorite suggests condensation or crystallization processes in the solar nebula or on the parent body of an asteroid. ## Mineral Associations This mineral was found in an enstatite-rich (silicon-rich) fragment of the Kaidun carbonaceous chondrite. It co-occurs with minerals such as enstatite, diopside, forsterite, plagioclase (albite), kamacite, troilite, schreibersite, and other rare minerals, including florenskyite (FeTiP). ## Localities The only confirmed locality for andreyivanovite worldwide is the Kaidun meteorite. This meteorite fell on December 3, 1980, near a military base in South Yemen. It is a unique breccia, containing rock fragments from various asteroid types.

Rarity

Extremely rare

For collectors

## Quality Criteria Andreyivanovite does not appear on the collector's market as a separate mineral. Its value is inextricably linked to the scientific and collectible value of the Kaidun meteorite itself. Specimens of this meteorite are extremely valuable to research institutions and specialized collectors due to their unique composition and the presence of many rare minerals. ## Popular Localities The only source is the Kaidun meteorite, which is not commercially available. Fragments are mainly found in institutional collections, such as the Vernadsky Institute in Moscow.

Care and storage

## Cleaning Due to its microscopic size and occurrence as inclusions within the host rock, individual grains of andreyivanovite are not subject to cleaning. A meteorite specimen containing this mineral should be protected from contamination. ## What to Avoid Contact with chemicals, especially acids, which could damage both andreyivanovite and the surrounding minerals, should be avoided. Moisture, which could lead to oxidation, should also be avoided. Samples should not be subjected to ultrasound or extreme temperature changes. ## Storage Specimens of the Kaidun meteorite containing andreyivanovite should be stored under stable conditions, preferably in a dry environment, in specialized meteorite storage containers that protect against dust and moisture.

Sources

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