Tetrataenite

A variety of Minerals

Tetrataenite specimen

What is Tetrataenite?

Tetrataenite is a native metal composed of chemically-ordered L10-type FeNi, recognized as a mineral in 1980. The mineral is named after its tetragonal crystal structure and its relation to the iron-nickel alloy, taenite. It is one of the mineral phases found in meteoric iron.

Uses & Applications

Tetrataenite is a candidate for replacing rare-earth permanent magnets such as samarium and neodymium since both iron and nickel are earth-abundant and inexpensive.

Market Value Factors

Pricing varies for every rock and mineral, so use these universal factors to gauge Tetrataenite before comparing listings or appraisals.

Size & Weight

Larger, intact specimens usually command higher prices.

Rarity & Demand

Scarce material or popular varieties sell at a premium.

Condition & Finish

Chips, repairs, and heavy wear lower value; clean prep helps.

Treatment & Provenance

Untreated specimens with documented locality are prized.

Applies to all rocks & minerals.

Tetrataenite Localities Map

See where Tetrataenite is found with a localities map, collecting zones, and geology context. Generate a sample map preview below.

Map preview
North ZoneCentral RidgeSouth Basin

Interactive map layers and collecting notes are available in the app.

Key Characteristics

Formation of Tetrataenite

Tetrataenite forms naturally in iron meteorites that contain taenite that are slow-cooled at a rate of a few degrees per million years, which allows for ordering of the Fe and Ni atoms. It is found most abundantly in slow-cooled chondrite meteorites, as well as in mesosiderites. At high (as much as 52%) Ni content and temperatures below 320 °C (the order-disorder transition temperature), tetrataenite is broken down from taenite and distorts its face centered cubic crystal structure to form the tetragonal L10 structure. The L10 phase can be synthetically produced by neutron- or electron-irradiation of FeNi below 593 K or by hydrogen-reduction of nanometric NiFe2O4, but only on a small scale. In 2015, it was reported that tetrataenite was found in a terrestrial rock - a magnetite body from the Indo-Myanmar ranges of northeast India.

Composition of Tetrataenite

Tetrataenite has a highly ordered crystal structure, appearing creamy in color and displaying optical anisotropy. Its appearance is distinguishable from taenite, which is dark gray with low reflectivity. FeNi easily forms into a cubic crystal structure, but does not have magnetic anisotropy in this form. Three variants of the L10 tetragonal crystal structure have been found, as chemical ordering can occur along any of the three axes.

Quick Facts

Physical Properties

Hardness (Mohs)
3.5

Chemical Properties

Chemical Formula
FeNi
Elements
Fe, Ni
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Tetrataenite FAQs

How do I identify Tetrataenite?

Tetrataenite can be identified by its hardness of 3.5 on the Mohs scale. Look for these key characteristics when examining specimens.

How hard is Tetrataenite?

Tetrataenite has a hardness of 3.5 on the Mohs scale. This gives it moderate hardness.

What is the formation of tetrataenite of Tetrataenite?

Tetrataenite forms naturally in iron meteorites that contain taenite that are slow-cooled at a rate of a few degrees per million years, which allows for ordering of the Fe and Ni atoms. It is found most abundantly in slow-cooled chondrite meteorites, as well as in mesosiderites. At high (as much as 52%) Ni content and temperatures below 320 °C (the order-disorder transition temperature), tetrataenite is broken down from taenite and distorts its face centered cubic crystal structure to form the tetragonal L10 structure. The L10 phase can be synthetically produced by neutron- or electron-irradiation of FeNi below 593 K or by hydrogen-reduction of nanometric NiFe2O4, but only on a small scale. In 2015, it was reported that tetrataenite was found in a terrestrial rock - a magnetite body from the Indo-Myanmar ranges of northeast India.

What is the composition of tetrataenite of Tetrataenite?

Tetrataenite has a highly ordered crystal structure, appearing creamy in color and displaying optical anisotropy. Its appearance is distinguishable from taenite, which is dark gray with low reflectivity. FeNi easily forms into a cubic crystal structure, but does not have magnetic anisotropy in this form. Three variants of the L10 tetragonal crystal structure have been found, as chemical ordering can occur along any of the three axes.

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