Ferrihydrite

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Ferrihydrite
Mine drainage from Ohio.jpg
Mine drainage from Ohio (USA) with ferrihydrite precipitation
General and classification
other names

IMA 1971-015

chemical formula Fe 3+ 10 O 14 (OH) 2
Mineral class
(and possibly department) 		Oxides and hydroxides
System no. to Strunz
and to Dana 		4.FE.35 ( 8th edition : IV / F.09)
04.03.02.02
Crystallographic Data
Crystal system hexagonal
Crystal class ; symbol dihexagonal-pyramidal; 6 mm
Space group P 6 3 mc (No. 186)Template: room group / 186
Lattice parameters a  = 5.95  Å ; c  = 9.06 Å
Formula units Z  = 1
Physical Properties
Mohs hardness not defined
Density (g / cm 3 ) not defined
Cleavage not defined
Break ; Tenacity not defined
colour yellowish brown to reddish brown, dark brown
Line color yellowish brown
transparency opaque
shine not defined

Ferrihydrite is a rarely occurring mineral from the mineral class of " oxides and hydroxides ". It crystallizes in the hexagonal crystal system with the chemical composition Fe 3+ 10 O 14 (OH) 2 , so it is an iron hydroxide.

Ferrihydrite only develops microscopic crystals and spherulitic mineral aggregates up to about 50  μm in size from yellowish brown to reddish brown or dark brown in color with yellowish brown streak color .

Etymology and history

Was first discovered in the ferrihydrite Altai in Kazakhstan and 1971. by Chukhrov, Zvyagin, Gorshkov, Ermilova and Rudnitskaya that the mineral as on its composition "hydrated iron" (English ferri c and hydr ated) designated.

Since the material for the analysis of the mineral comes from the "Belousovskii Mine" near Rudny and the "Ridder Mine" ( Leninogorsk Mine ) in East Kazakhstan , both pits are considered type localities . The type material of the mineral is kept in the Vernadsky Geological Museum (register no. 51508) and Fersman Mineralogical Museum of the Russian Academy of Sciences (register no. 76642) in Moscow (Russia).

classification

Already in the meanwhile outdated, but still in use 8th edition of the mineral classification according to Strunz , the ferrihydrite belonged to the class of "oxides and hydroxides" and there to the department of "hydroxides and oxidic hydrates (water-containing oxides with a layer structure)", where it together with akdalaite formed the unnamed group IV / F.09 .

In contrast , the 9th edition of Strunz's mineral systematics, which has been in force since 2001 and is used by the International Mineralogical Association (IMA), classifies ferrihydrite in the category of "hydroxides (without V or U)". This is further subdivided according to the possible presence of OH and / or H 2 O as well as the crystal structure, so that the mineral is classified according to its composition and structure in the sub-section “Hydroxides with OH, without H 2 O; Layers of edge-linked octahedra "can be found, where it is named after the" ferrihydrite group "with the system no. 4.FE.35 and the so far only hypothetical mineral hydromaghemite .

The systematics of minerals according to Dana , which is mainly used in the English-speaking world , assigns ferrihydrite to the class of "oxides and hydroxides" and there into the department of "oxide minerals". Here he can be found together with Akdalait in the unnamed group 04.03.02 within the sub-section “ Simple oxides with a cation charge of 3+ (A 2 O 3 ) ”.

Crystal structure

Ferrihydrite crystallizes hexagonally in the space group P 6 3 mc (space group no.186) with the average lattice parameters a  = 5.95  Å and c  = 9.06 Å and one formula unit per unit cell . Template: room group / 186

Education and Locations

Ferrihydrite forms as a precipitate in cold and hot springs with the help of iron-oxidizing microorganisms ( iron bacteria ), but is also found widely in the soluble fraction of soils and weathered rock . As Begleitminerale among others can goethite , hematite , lepidocrocite and various manganese oxides occur.

As a rare mineral formation, ferrihydrite could only be detected at a few sites, with around 60 sites being known so far (as of 2013). In addition to its type locality in the Altai Mountains, the mineral was also found in Kazakhstan in the “Sokolovskoe” iron mine in the Qostanai province .

In Germany, ferrihydrite was found, among other things, in the "Schmiedestollen" near Wittichen and in the Clara pit near Oberwolfach in Baden-Württemberg, on the slag heaps of the Ochsenhütte near Goslar and in the Hölltal near Lautenthal in Lower Saxony, on the slag heaps of the Hüstener union in the Sauerland (North Rhine -Westfalen), in the “Eckardthütte” near Leimbach (Mansfeld) in Saxony-Anhalt, in the “Weißer Hirsch” shaft near Neustädtel (Schneeberg) and in several pits on the Zechenberg near Hohenstein-Ernstthal in Saxony and on the slag dump on the Kammberg in the Joldelund municipality in Schleswig-Holstein.

In Austria, ferrihydrite has so far only been found on the Rotbachl in the Zamser Grund ( Zillertal ) and on the Silberberg near Reith in the Alpbachtal in the Inn Valley in Tyrol.

Other sites are found in Egypt, the Antarctic, Brazil, China, France, Greece, Italy, Japan, Poland, Russia, Slovakia, Spain, Tonga, the Czech Republic, Turkmenistan and the United States of America (USA).

Ferrihydrite was also detected in rock samples from the Barents Sea in the Arctic Ocean, in several rock samples from the Mid-Atlantic Ridge , from the Manus Basin in the Bismarck Sea , from the East Pacific Ridge and from the Franklin Seamount in the Pacific Ocean as well as in rock samples from the Red Sea .

See also

literature

  • FV Chukhrov, BB Zvyagin, AI Gorshkov, LP Ermilova, VV Balashova: Ferrihydrite. In: Izvestiya Akademii Nauk SSSR. (1973), pp. 23-33
  • Friedrich Klockmann : Klockmann's textbook of mineralogy . Ed .: Paul Ramdohr , Hugo Strunz . 16th edition. Enke , Stuttgart 1978, ISBN 3-432-82986-8 , pp. 555 (first edition: 1891).
  • F. Marc Michel, Lars Ehm, Sytle M. Antao, Peter L. Lee, Peter J. Chupas, Gang Liu, Daniel R. Strongin, Martin AA Schoonen, Brian L. Phillips, John B. Parise: The Structure of Ferrihydrite, a nanocrystalline material. In: Science 2007, Volume 316, No. 5832, pp. 1726–1729 doi : 10.1126 / science.1142525 ( PDF 225 kB )

Web links

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

Individual evidence

  1. ↑ a b IMA / CNMNC List of Mineral Names; October 2013 (PDF 1.5 MB)
  2. ↑ a b c d F. Marc Michel, Lars Ehm, Sytle M. Antao, Peter L. Lee, Peter J. Chupas, Gang Liu, Daniel R. Strongin, Martin AA Schoonen, Brian L. Phillips, John B. Parise: The Structure of Ferrihydrite, a Nanocrystalline Material. In: Science 2007, Volume 316, No. 5832, pp. 1726–1729 doi : 10.1126 / science.1142525 ( PDF 225 kB )
  3. ↑ a b Ferrihydrite , In: John W. Anthony, Richard A. Bideaux, Kenneth W. Bladh, Monte C. Nichols (Eds.): Handbook of Mineralogy, Mineralogical Society of America , 2001 ( PDF 67 kB )
  4. ↑ Mindat - Number of localities for ferrihydrite
  5. ↑ a b List of sites for ferrihydrite in the Mineralienatlas and Mindat