Trevorite

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Trevorite
Trevorite-Népouite-536296.jpg
Trevorite (grainy, black-green) and Népouite (light green) from Musongati, Rutana Province , Burundi ( overall size  6.2 cm × 3.6 cm × 2.4 cm)
General and classification
chemical formula NiFe 3+ 2 O 4
Mineral class
(and possibly department) 		Oxides and hydroxides
System no. to Strunz
and to Dana 		4.BB.05 ( 8th edition : IV / B.02)
02/07/02/05
Crystallographic Data
Crystal system cubic
Crystal class ; symbol cubic hexakisoctahedral; 4 / m  3  2 / m
Space group Fd 3 m (No. 227)Template: room group / 227
Lattice parameters a  = 8.34  Å
Formula units Z  = 8
Frequent crystal faces {111}
Physical Properties
Mohs hardness 5 ( VHN 50 = 937 ± 10)
Density (g / cm 3 ) measured: 5.164; calculated: 5.20
Cleavage is missing
Break ; Tenacity uneven
colour black to greenish black
Line color brown to dark brown
transparency opaque, transparent in the finest splinters
shine weak metallic luster
magnetism strong magnetic
Crystal optics
Refractive index n  = 2.3
Birefringence none, as it is optically isotropic

Trevorite is a rarely occurring mineral from the spinel supergroup within the mineral class of "oxides and hydroxides" with the idealized chemical composition NiFe 3+ 2 O 4 and is therefore chemically a nickel - iron - oxide .

Trevorite crystallizes in the cubic crystal system , but rarely develops small, octahedral crystals with a metallic sheen on the surfaces. It is usually found in the form of granular to massive mineral aggregates of black color with a tinge of green. Its line color , however, is brown to dark brown. The mineral is generally opaque and only transparent in the finest fragments.

Etymology and history

Trevorite was first discovered in 1920 by Major Tudor Gruffydd Trevor (1865-1958), then mining inspector for the Pretoria district (Transvaal, South Africa), in a small nickel deposit on the Bon Accord farm north of Barberton in the South African province of Mpumalanga . It was first described in 1921 by Andrew F. Crosse , who named the mineral after its discoverer.

Type material of the mineral is in the National Museum of Natural History in Washington, DC (USA) under the catalog no. 132464 and 132465 kept.

classification

The current classification of the International Mineralogical Association (IMA) counts the Trevorite to the spinel supergroup , where together with chromite , cochromite , coulsonite , cuprospinel , franklinite , gahnite , galaxite , hercynite , jacobsite , magnesiochromite , magnesiocoulsonite , magnesioferrite , magnetite , manganochromite , Spinel , vuorelainenite and zincochromite form the spinel subgroup within the Oxispinelle.

In the outdated, but still in use 8th edition of the mineral classification according to Strunz , trevorite belonged to the mineral class of "oxides and hydroxides" and there to the department of "oxides with a metal: oxygen ratio = 3: 4 (spinel type M 3 O 4 and related compounds ) ", Where together with cuprospinel, franklinite, jacobsite, magnesioferrite and magnetite, he created the group of" ferrite spinels "with the system no. IV / B.02 formed.

The 9th edition of Strunz's mineral systematics, which has been in effect since 2001 and is used by the IMA, also classifies Trevorite in the oxides division with a substance ratio of “metal: oxygen = 3: 4 and comparable”. This, however, is further divided according to the relative size of the participating cations , so that the mineral according to its composition in the subdivision to find "With only medium-sized cations" where it along with Brunogeierit , chromite, Cochromit, Coulsonit, Cuprospinell, Filipstadit , Franklinite , Gahnite, galaxite, hercynite, jacobsite, magnesiochromite, magnesiocoulsonite, magnesioferrite, magnetite, manganochromite, nichromite (N), qandilite , spinel, ulvöspinell , vuorelainenite and zinc chromite the "spinel group" with the system no. 4.BB.05 forms.

The systematics of minerals according to Dana , which is mainly used in the English-speaking world , assigns Trevorite to the class of "oxides and hydroxides" and there in the section "multiple oxides". Here it is together with magnesioferrite, jacobsite, magnetite, franklinite, cuprospinel and brunogeierite in the " iron subgroup " with the system no. 07.02.02 to be found in the subsection “Multiple Oxides (A + B 2+ ) 2 X 4 , Spinel Group ”.

Chemism

The first analysis of a large number of samples from the Bon Accord type locality by Crosse revealed a composition of 40.30% nickel oxide, 49.30% iron oxide and 6.50% silicon dioxide ( silica ) and traces of phosphorus (0.13%) and Calcium oxide (0.20%). From the empirical composition, Crosse calculated a metal content of 29.6% nickel and 35.7% iron, but did not give a chemical formula in his first description.

The composition of Trevorite was redefined in 1923 by Thomas Leonard Walker and therefore contains 31.9% NiO and 68.1% Fe 2 O 3 . Walker gives the oxide formula as NiO · Fe 2 O 3 and the empirical formula as NiFe 2 O 4 .

By partially substituting iron for nickel, the chemical composition of trevorite varies between NiFe 3+ 2 O 4 and (Ni 6 Fe 4 ) Fe 2 O 4 . Traces of cobalt and magnesium can also be built into the nickel position.

Crystal structure

Trevorite crystallizes cubically in the structure of spinel with the space group Fd 3 m (space group no. 227) , the lattice parameter a  = 8.34  Å and 8 formula units per unit cell . Template: room group / 227

properties

Trevorite is very similar to magnetite in many properties and shows, for example, a strong magnetism . In contrast to this, however, Trevorite shows no tendency to split and breaks with uneven fracture surfaces.

With a Mohs hardness of 5, trevorite is one of the medium-hard minerals that, like the reference mineral apatite (hardness 5), scratch itself with a pocket knife .

Education and Locations

Trevorite formed in the small, tabular nickel deposit Bon Accord in the contact zone between quartzite and serpentinized and chloritized ultrabasites or ultramafites . As accompanying minerals may vary by locality, among others, goethite , Heazlewoodite nickel, Millerit , dignified nickel , Nimit , Reevesit , talc , Violarite and Willemseite occur.

As a rare mineral formation, Trevorite could only be detected at a few sites, whereby so far (as of 2018) fewer than 20 sites have been documented. Besides its type locality Bon Accord and in the nearby talc mine Scotia in Mpumalanga is Trevorit found in South Africa still in the mine Karee at Rustenburg and Morokweng crater in the province of North West .

The only known site in Germany so far is the mine dump at Lichtloch 25 of the Gottesbelohnung copper-silver smelter near Hettstedt in Saxony-Anhalt.

So far, the mineral is known throughout Europe only from the slag heaps near Agios Konstantinos (Kamariza) in the Greek municipality Lavrio (Attica), from Szklary in the Polish powiat Ząbkowicki . Another site in Italy, more precisely the Funtana Raminosa mine near Gadoni in the province of Nuoro (Sardinia) has not yet been confirmed.

Worldwide Trevorit was still found on cone No. 32 in the McBride Volcanic Province of Queensland as well as on Mount Clifford and in the Marriott's nickel prospecting at Ten Mile Outcamp in the administrative region of Leonora Shire in Western Australia, near Musongati in the Rutana Province of Burundi, in the Phokphur ore deposit in the Tuensang district of the Indian state of Nagaland , in the Hatrurim formation within the Israeli Negev desert as well as at Hatfield near Gabbs in Nye County of Nevada and in a soap deposit on Josephine Creek in the county of Oregon in the United States of America (USA ).

Trevorite was also detected together with cobalt and magnetite in rock samples from the Mid-Atlantic Ridge , which were collected during one of the expeditions of the research vessel Albatross at position 23 ° 58 ′  N , 38 ° 56 ′  W. Another find in the Logatchev-1 hydrothermal field , on the other hand, has so far been considered questionable or could not be verified.

Furthermore, trevorite was identified as a component of various meteorites , including a previously unnamed meteorite that was found in Kazakhstan in 2017 ; in the stone meteorite Khatyrka (Federal District Far East, Russia) and in the Canyon Diablo found near the Barringer Crater in Arizona .

use

Due to its rarity, trevorite is of no economic importance and only of interest to mineral collectors despite its high nickel content of almost 17%.

See also

literature

  • Andrew F. Crosse: A rich nickel ore . In: Journal of the Chemical, Metallurgical, and Mining Society of South Africa . tape 21 , 1921, pp. 126–127 ( rruff.info [PDF; 272 kB ; accessed on August 19, 2018]).
  • TL Walker : Trevorite, a distinct mineral species . In: Contributions to Canadian Mineralogy, University of Toronto Studies, Geology Series . tape 16 , 1923, pp. 53-54 .
  • ET Wherry: Redefinition of species . In: American Mineralogist . tape 9 , 1924, pp. 97-98 ( rruff.info [PDF; 122 kB ; accessed on August 19, 2018]).
  • SA de Waal: Nickel minerals from Barberton, South Africa: I. Ferroan trevorite . In: American Mineralogist . tape 54 , 1969, p. 1204–1208 ( rruff.info [PDF; 300 kB ; accessed on August 20, 2018]).
  • SA de Waal: Mineralogical notes: nickel minerals from Barberton, South Africa: V. trevorite, redescribed . In: American Mineralogist . tape 57 , 1972, p. 1524–1527 ( rruff.info [PDF; 228 kB ; accessed on August 20, 2018]).
  • MC Blesa, Ulises Amador, Emilio Morán, N. Menéndez, JD Tornero, Juan Rodríguez-Carvajal: Synthesis and characterization of nickel and magnesium ferrites obtained from α-NaFeO 2 . In: Solid State Ionics . tape 63 , no. 5 , 1993, p. 429-436 , doi : 10.1016 / 0167-2738 (93) 90140-X .
  • B. O'Driscoll, PL Clay, PL Cawthorn, Davide Lenaz, J. Adetunji, A. Kronz: Trevorite: Ni-rich spinel formed by metasomatism and desulfurization processes at Bon Accord, South Africa? In: Mineralogical Magazine . tape 78 , 2014, p. 145–163 , doi : 10.1180 / minmag.2014.078.1.11 .

Web links

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

Individual evidence

  1. ↑ 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.  188 (English).
  2. ^ IMA / CNMNC List of Mineral Names; March 2018 (PDF 1.65 MB)
  3. ↑ Webmineral - Trevorite (English)
  4. ↑ a b c Helmut Schrätze , Karl-Ludwig Weiner : Mineralogie. A textbook on a systematic basis . de Gruyter, Berlin; New York 1981, ISBN 3-11-006823-0 , pp.  374 .
  5. ↑ a b c d e f g h i Trevorite . In: John W. Anthony, Richard A. Bideaux, Kenneth W. Bladh, Monte C. Nichols (Eds.): Handbook of Mineralogy, Mineralogical Society of America . 2001 (English, handbookofmineralogy.org [PDF; 69  kB ; accessed on August 19, 2018]).
  6. ↑ a b c Richard V. Gaines, H. Catherine W. Skinner, Eugene E. Foord, Brian Mason , Abraham Rosenzweig: Dana's New Mineralogy . 8th edition. John Wiley & Sons, New York (et al.) 1997, ISBN 0-471-19310-0 , pp. 300-301 .
  7. ↑ 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 .
  8. ↑ a b Andrew F. Crosse: A rich nickel ore . In: Journal of the Chemical, Metallurgical, and Mining Society of South Africa . tape 21 , 1921, pp. 126–127 ( rruff.info [PDF; 272 kB ; accessed on August 19, 2018]).
  9. ↑ Cristian Biagioni, Marco Pasero: The systematics of the spinel-type minerals: An overview . In: American Mineralogist . tape 99 , no. 7 , 2014, p. 1254–1264 , doi : 10.2138 / am.2014.4816 (English, preliminary version online [PDF]).
  10. ^ ET Wherry: Redefinition of species . In: American Mineralogist . tape 9 , 1924, pp. 97-98 ( rruff.info [PDF; 122 kB ; accessed on August 19, 2018]).
  11. ↑ Mindat - Number of localities for Trevorite (English)
  12. ↑ a b c d List of places where Trevorite was found in the Mineralienatlas and Mindat
  13. ↑ Richard A.Schmidt, Klaus Keil: Electron microprobe study of spherules from Atlantic Ocean sediments . In: Geochimica et Cosmochimica Acta . tape 30 , no. 5 , May 1966, pp. 471-474 , doi : 10.1016 / 0016-7037 (66) 90058-5 .