Akaganéite
- IMA 1962-004
- Fe8 (OH, O, C ) or 17 - β Fe 3 O (OH, Cl)
- ( Fe3 , Ni2 ) 8 (OH, O) 16Cl1.25 · nH2O
Akaganeite is a rarely occurring mineral from the mineral class of " oxides and hydroxides ". It crystallizes in the monoclinic crystal system with the idealized composition of β - Fe 3 O (OH, Cl), and is therefore a chemical point of an iron ( III) oxide hydroxide with iron in the modification of β - Fe. The values given in the parentheses formula parts hydroxide and chlorine may be in the formula each represent each other (substitution, Diadochie ), but are always in the same proportions to the other components of the mineral.
Akaganeite developed microscopic small spindle-shaped crystals up to about five microns in length with diamond to metal- like luster, which are often arranged in tufted mineral aggregates. In general, however, he finds himself in the form of fine -grained to massive aggregates and earthy, matte, powdery coatings. The crystals themselves are transparent to translucent, even if aggregate forms look more opaque. The color of the mineral varies between yellowish brown and russet, his stroke color always yellowish brown contrast.
Etymology and history
The mineral was first discovered by Dr. M. Nambu of the University in Sendai " Akagane Mine" near Esashi in Iwate Prefecture on the Japanese island of Honshu and named after its type locality. Described in detail, it was founded in 1962 by AL Mackay.
Classification
In the now outdated but still in use 8th edition of the mineral classification by Strunz the akaganeite belonged to the class of " oxides and hydroxides " and then to the Department of " hydroxides and oxide hydrates ( hydrous oxides with layered structure ) ", where he was named the " akaganeite group "with the system no. Formed IV/F.06 and the other members boehmite, diaspore, Feitknechtit, Feroxyhyt, goethite, Groutit, lepidocrocite, manganite, schwertmannite and Tsumgallit.
The 9th edition used since 2001, valid and of the International Mineralogical Association (IMA ) of the Strunz'schen Mineral classification assigns the akaganeite also in the class of " oxides and hydroxides ," there, however, in the department of " oxides with the molar ratio of metal: oxygen = 1: 2 and comparable " one. This is also further divided according to the relative size of the involved cations and the crystal structure, so that the mineral according to its composition and its construction in the subdivision " with large (± medium-sized ) cations; " Is to find where it together with coronadite, Henrymeyerit, hollandite, manjiroite, Mannardit, Priderit and Redledgeit the " tunnel structures Hollanditgruppe "with the system no. 4.DK.05 forms.
The mainly common in English-speaking classification of minerals according to Dana assigns the akaganeite in the class of " oxides and hydroxides " and there in the department of " hydroxides and hydroxy- oxides " one. Here he is the only member of the unnamed group 06:01:06 within the subdivision " hydroxides and hydroxy- oxides having the formula: X3 O OH " to find.
Education and Locations
Akaganeite is formed by the weathering of pyrrhotite in the oxidation zone of limonite deposits and is an important component in some soils and geothermal brines. Also in Erzknollen in the seabed and as a corrosion product in some meteorites may arise akaganeite. As an accessory mineral can, you still Hibbingit occur next to pyrrhotite.
A rare mineral akaganeite formation could be detected only in a few localities, where so far (as of 2013) are about 50 localities known as. Its type locality " Akagane Mine " is the only known locality in Japan.
In Germany, you know the mineral so far only from the Clara mine in Oberwolfach in Baden- Württemberg, the slag heaps of Ochsenhütte and Herzog- Julius- hut in the Lower Saxony district of Goslar, Genna zinc smelter at Letmathe in North Rhine -Westphalia and the shaft 366 of the deposit Schneeberg / schlema / Alberoda in Saxony.
Furthermore, it was akaganeite in the " Campo del Cielo " meteorite in Argentina, the near São Francisco do Sul in the Brazilian state of Santa Catarina discovered " Santa Catarina Meteorite " in Nantan meteorite in the Chinese province of Guangxi, in Dronino meteorite in Russia, in Muonionalusta meteorite found in the Swedish municipality of Pajala.
Other known localities include Visé - Richelle in Belgium, the " Strathcona Mine" at Levack in the Canadian province of Ontario, the ancient slag heaps at Lavrio in the Greek region of Attica, the slag heaps at Campiglia Marittima and Piombino in Italy, the " Animas Mine " at La Mura in the municipality of Trincheras in Mexico, White Iceland ( Bay of Plenty ) in New Zealand, the Kaskasnjuntschorr in the Chibinen on the Russian Kola Peninsula and the Aldanhochland in Siberia, Zlata Bana in Slovakia, the iron ore deposit" Kerchenskoe " near Kerch on the Crimean peninsula in Ukraine, the " Gravel Hill Mine" near St Agnes (Cornwall ) in the United Kingdom as well as several places in various states across the United States.
Even in rock samples from the Mid-Atlantic Ridge and the Red Sea ( deep drilling Atlantis II ) and outside the Earth from the Moon in the Apollo 16 - Luna 24 mission brought back and rock samples Akaganeite could be detected.
Crystal structure
Akaganeite crystallizes in the monoclinic space group I2 / m ( Raumgruppen-Nr. 12) with the lattice parameters a = 10.60 Å; b = 3.03 Å; c = 10.51 Å and β = 90.2 ° and a formula unit per unit cell.