Akaganéite

Akaganeite
A piece of the mineral akaganeite. Exhibit of the "Earth and Man" Museum in Sofia, Bulgaria. Discovered in Kaskasnyunchorr, Khibiny Massif, Kola Peninsula, Russia
General
Category Oxide mineral
Formula
(repeating unit)		 Fe3+O(OH,Cl)
Strunz classification 4.DK.05
Crystal system Monoclinic
Crystal class Prismatic (2/m)
(same H-M symbol)
Space group I2/m
Unit cell a = 10.561, b = 3.031
c = 10.483 [Å]; β = 90.63°; Z = 1
Identification
Color Yellowish brown, rusty brown
Luster Earthy
Streak Brownish yellow
Diaphaneity Transparent, translucent
Specific gravity 3.52

Akaganeite is an iron(III) oxide-hydroxide / chloride mineral with formula: Fe3+O(OH,Cl) e.g.; β-FeO(OH). It is formed by the weathering of pyrrhotite (Fe1−xS). Nickel also has been reported in the structure. It has a monoclinic crystal structure, a metallic luster and a brownish yellow streak. It is named after the Akagane mine in Iwate, Japan, in which it was discovered. It has also been found in widely dispersed locations around the world and in rocks from the Moon that were brought back during the Apollo Project. The occurrences in meteorites and the lunar sample are thought to have been produced by interaction with Earth's atmosphere. It has been detected on Mars through orbital imaging spectroscopy [1].

It was described by the Japanese mineralogist Matsuo Nambu in 1968[2] but named as early as 1961[3]. The name comes from the topotype, the Akagane Mine in Iwate Prefecture, Japan.

See also

List of minerals

References

  1. ↑ Carter et al. 2015 "Orbital detection and implications of akaganéite on Mars" Icarus, 253: 296-310
  2. ↑ 岩手県赤金鉱山産新鉱物赤金鉱 (β-FeOOH) について [[https://www.jstage.jst.go.jp/article/ganko1941/59/4/59_4_143/_pdf New mineral Akaganeite, β-FeOOH, from Akagane Mine, Iwate Prefecture, Japan]], 岩石鉱物鉱床学会誌, 59 巻 4 号, 1968 年
  3. ↑ Alan Lindsay Mackay, "β-ferric oxyhydroxide, akaganéite [sic]", in Mineralogical Magazine, 33: 270-280, 1962, citing a private communication by Matsuo Nambu (1961)
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