Tetrataenite

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Tetrataenite
Tetrataenite-138027.jpg
Pale silvery tetrataenite crystals in the meteorite Nuevo Mercurio , Zacatecas , Mexico ( total size of the sample 2.7 cm × 2.0 cm × 2.0 cm )
General and classification
other names

1979-076

chemical formula FeNi
Mineral class
(and possibly department) 		elements
System no. to Strunz
and to Dana 		1.AE.10 ( 8th edition : I / A.08)
01.01.11.03
Crystallographic Data
Crystal system tetragonal
Crystal class ; symbol ditetragonal-dipyramidal; 4 / m  2 / m  2 / m
Space group P 4 / mmm (No. 123)Template: room group / 123
Lattice parameters a  = 2.53  Å ; c  = 3.58 Å
Formula units Z  = 1
Physical Properties
Mohs hardness 3.5 to 4; VHN 25 = 170 to 200
Density (g / cm 3 ) 8.28
Cleavage is missing
colour cream-colored, gray-white
Line color Gray
transparency opaque (opaque)
shine Metallic luster
magnetism strong magnetic

Tetrataenite is a rarely occurring mineral from the mineral class of "elements (including natural alloys or intermetallic compounds, carbides, nitrides, phosphides and silicides)" with the chemical composition FeNi and is therefore chemically a natural alloy , more precisely an intermetallic compound made of iron and nickel in a molar ratio of 1: 1.

Tetrataenite crystallizes in the tetragonal crystal system , but has so far only been discovered in the form of irregular crystallites and grains up to about 100 μm. The mineral is opaque in every form and appears cream-colored with a metallic sheen in the reflected light microscope .

As a typical meteorite mineral, tetrataenite has so far been discovered almost exclusively in various meteorites that have fallen on Earth.

Etymology and history

Tetrataenite was first discovered in mineral samples from the Estherville meteorite , which fell on May 10, 1879 near the city ​​of the same name in the US state of Iowa . The mineral was first described in 1980 by Roy S. Clarke Jr. and Edward RD Scott, who named it after its tetragonal symmetry and chemical similarity to taenite (γ- (Fe, Ni)).

Type material , i.e. mineral samples from the type locality, are stored in the National Museum of Natural History in Washington, DC (USA) under catalog no. 1025 kept in the meteorite collection.

classification

Already in the outdated, but partly still in use 8th edition of the mineral classification according to Strunz , the tetrataenite belonged to the mineral class of the "elements" and there to the department of "metals and intermetallic alloys (without semimetals)", where it together with Awaruit , Jedwabit , Nickel and Taenit the "nickel series" with the system no. I / A.08 formed.

The 9th edition of Strunz's mineral systematics , which has been in effect since 2001 and is used by the International Mineralogical Association (IMA), also classifies the tetrataenite in the “Metals and Intermetallic Compounds” department. However, this is further subdivided according to the predominant metals in the compound, which have been divided into metal families according to their related properties. Tetrataenite can be found here according to its composition in the subdivision "iron-chromium family", where it only together with Taenit the "Taenite group" with the system no. 1.AE.10 forms.

The systematics of minerals according to Dana , which is predominantly used in the English-speaking world , assigns the Tetrataenite to the class and there the department of the same name of "elements". Here it is together with Eisen , Kamacit , Taenit, Awaruit, Nickel and Wairauit in the " iron-nickel group " with the system no. 01.01.11 to be found in the subsection "Elements: Metallic elements other than the platinum group".

Chemism

The electron beam microanalysis of mineral samples from 14 meteorites revealed the following empirical composition for tetrataenite in% by weight:

  • Ni 48–57%, ⌀ 5l%
  • Fe 44–52%, ⌀ 49%
  • Cu 0, ll – 0.36%, ⌀ 0.20%
  • Co <0.02–2.0%, ⌀ 0.08%
  • P <0.01%

In the idealized composition FeNi, tetrataenite contains 48.76% by weight iron and 51.24% nickel. As foreign admixtures , however, the mineral can be up to 0.2% copper and traces of cobalt and phosphorus contained.

Crystal structure

Crystal structure of tetrataenite

Tetrataenite crystallizes isostructurally with tetra-auricupride (CuAu) in the tetragonal crystal system in the space group P 4 / mmm (space group no. 123) with the lattice parameters a  = 2.53  Å and c  = 3.58 Å and one formula unit per unit cell . Template: room group / 123

The crystal structure of tetraenite consists of two primitive, tetragonal unit cells ( square columns ), with either iron (Fe) or nickel (Ni) atoms at the 8 corner points. These two unit cells are pushed into each other by half a lattice parameter, so that body-centered unit cells with Fe at the corners and Ni in the center or, conversely, Ni at the corners and Fe in the center. If Ni is assumed to be in the center, it is surrounded by 8 Fe and 4 Ni as the closest neighbors. One can also say that Ni is coordinated 8-fold to Fe and 4-fold to Ni .

Due to the slight differences in the atomic radii of iron (140 pm) and nickel (135 pm) and the regular arrangement of the two in the crystal lattice (superstructure), the structure as a whole is reduced to a tetragonal symmetry instead of forming a cubic substitution solid solution as in the cubic crystallizing starting metals iron and nickel would be expected.

In a study published in 1995 on the superstructure of tetrataenite in the Saint Severin meteorite , T. Tagai and H. Takeda argued that tetrataenite could only be metrically tetragonal and that its structure actually has an orthorhombic or monoclinic symmetry. The lattice parameters measured by them are a  = 3.581 (2) Å; b  = 3.582 (2) Å; c  = 3.587 (2) Å; α = 90.03 (3) °; β = 90.04 (3) ° and γ = 90.00 (3) °. However, the tetrataenite in the Saint Severin does not show a perfect order, but contains an average of 15% randomly arranged iron and nickel atoms. In addition, the measured lattice constants show a clear tendency towards tetragonal symmetry within the experimentally occurring measurement uncertainties .

Education and Locations

Tetrataenite mainly forms in meteorites that cool extremely slowly with a cooling rate of a few degrees per million years and more slowly, down to below the order-disorder transition temperature of 320 ° C. Only then can the Fe and Ni atoms arrange themselves regularly in the taenite. The typical accompanying minerals in meteorites are kamacite , troilite and taenite as well as various silicates.

Tetrataenite could be visually identified in over 50 chondrites and mesosiderites at the time of the first description . In total, however, around 110 meteorites (as of 2017) are known in which tetrataenite was found. In addition to its type locality , the Estherville meteorite, which was discovered in Iowa , Tetrataenite was also found in a large number of meteorites in various states of the USA such as the Emery found in South Dakota in 1962 and the Morristown found in Tennessee in 1887 as two of the four known A3- Mesosiderites.

Other significant meteorite finds for Tetrataenite are among others

  • Poland
    • Łowicz , one of four known A3 mesosiderites that hit the area around Łowicz on March 12, 1935 as a true meteor shower of a total of 58 stones with a total weight of 59 kg .
    • Morasko , including type locality for Czochralskiit and Moraskoit , which was found on November 12, 1914 near the village of the same name in the Greater Poland Voivodeship .

Other meteorites with tetrataenite were found in Algeria (NWA 4801), Angola (Ehole), Antarctica (Allan Hills), Argentina (Malotas), Australia ( Tenham ), Bangladesh (Bhola, Patwar), Brazil (Rio do Pires, Parambu, Ipiranga, Vicência, Santa Catharina, Avanhandava, Buritizal, São José do Rio Preto), Burkina Faso (Bilanga), Chile ( Imilac , Vaca Muerta), Finland ( Bjurböle ), India ( Bishunpur ), Indonesia (Ngawi), Iran (Veramin), Ireland (Limerick), Italy (Alfianello, Trenzano, Vigarano), Japan ( Kesen ), Yemen ( Kaidun ), Cameroon (Galim), Canada (Benton), Kazakhstan (Efremovka), Morocco (Kheneg Ljouâd), the Netherlands (Uden), Oman (Dhofar 225), Russia (Budulan, Chinga , Krasnojarsk , Marjalahti, Seymchan , Ochansk), Serbia (Jelica, Soko-Banja), Spain (Barea, Guareña, Olivenza, Sena), Czech Republic ( Tieschitz), Turkey (Didim), Ukraine (Elenovka, Krymka, Zhovtnevyi) and the United Kingdom (Appley Bridge, Barwell, Bovedy, Wold Cottage) .

Metallic nickel iron is very rarely found in terrestrial rock as it is only formed in the presence of strong reducing agents such as hydrogen (H 2 ) and carbon (C). Such an environment is found, for example, in serpentinized peridotites and in volcanic rocks with assimilated carbonaceous material.

One of the extremely rare, purely terrestrial sites for tetrataenite is an ophiolite - and nickel-containing magnetite ore body in the tectonic border area India - Myanmar northeastern India.

use

So far, no specific use of tetrataenite is known. However, due to its excellent magnetic properties, the mineral has already received a lot of attention in the scientific community, as there is a possibility that it could be developed as an alternative to REE -based permanent magnets .

See also

literature

  • Roy S. Clarke Jr., Edward RD Scott: Tetrataenite- ordered FeNi, a new mineral in meteorites . In: American Mineralogist . tape 65 , 1980, pp. 624–630 ( rruff.info [PDF; 887 kB ; accessed on January 8, 2018]).

Web links

Commons : Tetrataenite  - collection of images, videos and audio files

Individual evidence

  1. ^ IMA / CNMNC List of Mineral Names; September 2017 (PDF 1.67 MB)
  2. ↑ a b c d Hugo Strunz , Ernest H. Nickel : Strunz Mineralogical Tables. Chemical-structural Mineral Classification System . 9th edition. E. Schweizerbart'sche Verlagbuchhandlung (Nägele and Obermiller), Stuttgart 2001, ISBN 3-510-65188-X , p.  41 .
  3. ↑ a b Stefan Weiß: The large Lapis mineral directory. All minerals from A - Z and their properties . 6th completely revised and supplemented edition. Weise, Munich 2014, ISBN 978-3-921656-80-8 .
  4. ↑ a b c Tetrataenite . In: John W. Anthony, Richard A. Bideaux, Kenneth W. Bladh, Monte C. Nichols (Eds.): Handbook of Mineralogy, Mineralogical Society of America . 2001 ( handbookofmineralogy.org [PDF; 118  kB ; accessed on January 7, 2018]).
  5. ↑ a b Bibhuranjan Nayak, Franz Michael Meyer: Tetrataenite in terrestrial rock . In: American Mineralogist . tape 100 , no. 1 , 2015, p. 209–214 , doi : 10.2138 / am-2015-5061 (accessed via De Gruyter Online).
  6. ↑ Estherville in the Meteoritical Bulletin Database (English)
  7. ↑ Mindat - Tetrataenite (English)
  8. ^ Roy S. Clarke Jr., Edward RD Scott: Tetrataenite-ordered FeNi, a new mineral in meteorites . In: American Mineralogist . tape 65 , 1980, pp. 624–630 ( rruff.info [PDF; 887 kB ; accessed on January 8, 2018]).
  9. ↑ Webmineral - Tetrataenite (English)
  10. ↑ T. Tagai, H. Takeda: Superstructure of tetrataenite from the Saint Severin meteorite . In: Journal of Crystallography . tape 210 , 1995, pp. 14–18 ( rruff.info [PDF; 361 kB ; accessed on January 8, 2018]).
  11. ↑ a b Number of A3 mesosiderites in the Meteoritical Bulletin Database
  12. ↑ a b List of sites for tetrataenite in the Mineralienatlas and Mindat