Haxonite

Chemical formula: (Fe,Ni)<sub>23</sub>C<sub>6</sub>

Haxonite is a rare iron-nickel carbide, found almost exclusively in iron meteorites, forming microscopic inclusions.

## Characteristics Haxonite is a rare mineral from the carbide group, being a natural iron-nickel alloy. It forms microscopic, irregular grains and lamellae, most often as inclusions in kamacite – another mineral found in iron meteorites. Due to its composition and occurrence, it is a subject of scientific research into processes occurring in the cores of asteroids. Its observation usually requires the use of a microscope, as macroscopic crystals are not known. ## Physical Properties As an opaque and metallic mineral, haxonite is characterized by a strong, metallic luster. It is hard, with a Mohs hardness estimated at 5.5 to 6. Its density is high, approximately 7.66 g/cm³, which is typical for iron-rich minerals. ## Colors and Varieties This mineral has a color ranging from creamy white to tin-white, often with a yellowish tint. No color varieties or commercial varieties are distinguished. ## History and Name The name haxonite comes from the surname of Howard Horace Nininger (1887-1986), an American pioneer in meteorite research, who used the pseudonym "H.H. Haxon". The mineral was first described in 1971 by E.R.D. Scott, who found it in the Toluca and Coahuila meteorites. Approval by the International Mineralogical Association (IMA) occurred in the same year. ## Applications Haxonite has no industrial or commercial applications. Its significance is purely scientific and collectible, as a component of rare meteorite types.

Properties

Mohs hardness
5.5-6
Luster
Metallic
Streak
Black
Density
7.66
Cleavage
None
Fracture
Uneven
Transparency
Opaque
Crystal system
Isometric

Diagnostic features

## Identification Identification of haxonite is possible almost exclusively through advanced laboratory techniques, such as metallography (microscopic observations of etched surfaces) and X-ray microanalysis (EDS/WDS). In microscopic studies under reflected light, it differs from the surrounding kamacite by a slightly different color and a harder reaction to polishing. ## Distinguishing from Similar Minerals Haxonite occurs in paragenesis with other meteoritic minerals. It is distinguished from kamacite (Fe,Ni) by its higher hardness and resistance to nitric acid etching. It differs from cohenite ((Fe,Ni,Co)₃C) by its chemical composition and subtle optical properties. It is distinguished from schreibersite ((Fe,Ni)₃P) by the absence of phosphorus in its composition. Distinguishing these phases requires specialized equipment. ## Crystal Forms Haxonite forms exclusively anhedral (irregular) grains and lamellae of microscopic size, usually not exceeding several tens of micrometers. It does not form well-developed crystals.

Geological environment

## Genesis Haxonite is a mineral formed under conditions of extremely slow cooling of an iron-nickel alloy, which prevailed in the cores of large asteroids and small planets. It crystallizes in iron meteorites (octahedrites and hexahedrites) and in metallic fragments of some chondrites and mesosiderites. It is a product of solid-state decomposition of primary taenite (a high-temperature variety of the Fe-Ni alloy). ## Mineral Associations This mineral occurs inseparably with other meteoritic minerals, primarily kamacite and taenite, forming characteristic intergrowths with them. It also co-occurs with cohenite, schreibersite, troilite, and graphite. ## Localities Haxonite is found exclusively in meteorites. It has been identified in many known falls, including Toluca and Coahuila (Mexico), Canyon Diablo (USA), Sikhote-Alin (Russia), Campo del Cielo (Argentina), as well as in the Polish Morasko meteorite.

Rarity

Very rare

For collectors

## Quality Criteria The collectible value of haxonite is inextricably linked to the value of the meteorite in which it is found. As it is a microscopic phase, it is not subject to independent quality assessment. For collectors specializing in meteorites, the value of a specimen (slice or slab) is enhanced by the presence of rare mineral phases, confirmed by scientific research. Visual appeal can be provided by a well-etched surface showing Widmanstätten structures with inclusions of haxonite and other minerals. ## Popular Localities Meteorite specimens in which the presence of haxonite has been documented come from well-known meteorite fields, such as Toluca in Mexico, Canyon Diablo in Arizona (USA), and Sikhote-Alin in Russia. Fragments of these meteorites are available on the collector's market.

Care and storage

## Cleaning Meteorite specimens containing haxonite are stable, but should be handled with care. Cleaning should be limited to removing dust with a soft brush or compressed air. Avoid water and any chemical agents. ## What to Avoid The greatest threat to iron meteorites, in which haxonite occurs, is moisture, which can cause rusting (oxidation). Absolutely avoid contact with water, acids, bases, and other chemicals. They should also not be heated. ## Storage Meteorite specimens with haxonite should be stored in a dry environment, preferably in a sealed container (e.g., a membrane box) with a desiccant (e.g., silica gel). Display should be in a closed display case, away from sources of moisture and sudden temperature changes.

External references

Sources

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