Akaganéite is a chlorine mineral/iron (III) oxide-hydroxide that is formed by the weathering pyrrhotite. Akaganeite is named after the Akagane mine in Iwate, Japan, where it was first discovered.
Properties of Akaganéite
The following are the key properties of Akaganeite:
- Cell Data
- Space Group: I2/m.
- a = 10.561(4)
- b = 3.031(1)
- c = 10.483(4)
- β = 90.63(4)°
- Z = 8
- Crystal Data
- Monoclinic
- Point group: 2/m
- Tiny spindlelike quasi-single crystals are up to 5 µm in length; in bundles of such rods; commonly fine-grained massive to powdery.
- X-ray powder pattern: synthetic FeO(OH). 3.333 (100), 2.5502 (55), 7.467 (40), 2.2952 (35), 1.6434 (35), 5.276 (30), 2.6344 (25)
- Chemical Composition
| Elements |
Content 1 |
Content 2 |
Content 3 |
| Fe2O3 |
78.23 |
69.0 – 76.0 |
89.86 |
| H2O+ |
10.20 |
- |
10.14 |
| H2O- |
4.96 |
- |
- |
| SiO2 |
3.10 |
- |
- |
| Al2O3 |
1.21 |
- |
- |
| FeO |
0.82 |
|
- |
| Na2O |
0.62 |
- |
- |
| K2O |
0.19 |
- |
- |
| Cl |
- |
3.6 – 6.3 |
- |
| NiO |
- |
0.4 – 5.6 |
- |
| Total |
99.33 |
|
100.00 |
- Optical Properties
- Optical Class: Biaxial.
- α = n.d.
- β = n.d.
- γ = n.d.
- 2V(meas.) = n.d.
- Estimated Properties
| Electron density |
Bulk density (electron density)=3.64 g/cm3
note: specific gravity of akaganeite =3.75 g/cm3 |
| Photoelectric |
PEAkaganeite = 18.39 barns/electron
U=PEAkaganeite x ρElectron Density= 66.91 barns/cm3 |
| Fermion index |
Fermion index = 0.01
Boson index = 0.99 |
| Radioactivity |
Akaganeite is not radioactive |
How to Identify Akaganéite
Akaganeite can be identified in the field by its brown and rusty brown opaque appearance. It has an adamantine-metallic lusture with a brownish yellow streak. This mineral forms a loose and poorly-coherent pulverulent mass.
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A piece of the mineral Akaganéite. Exhibit of the "Earth and Man" Museum in Sofia, Bulgaria. Discovered in Kaskasnyunchorr, Khibiny Massif, Kola Peninsula, Russia. Image Credit: Vassia Atanassova – Spiritia”
Global Distribution
Globally, akaganeite can be found in the following locations:
- Japan- Akagane mine, Iwate Prefecture
- Germany-Oberwolfach, Black Forest
- England- Warham Marshes, Norfolk
- Belgium- Richelle
- USA- In Black Rock, Humboldt Co., Nevada
-North of the Santa Ni˜no mine, Santa Cruz Co, Arizona
-Questa, Taos Co., New Mexico
-Duluth Gabbro complex, near Hibbing, St. Louis Co., Minnesota
-Las Animas mine, La Mur, Trincheras, Sonora
Occurrence of Akaganéite and Useful Mineral Association
Akaganeite occurs in certain geothermal brines, oxidation zones of pyrrhotite-bearing iron sulphide deposits and sea-floor nodules. Akaganeite is formed as a corrosion product of some meteorites.
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