Akaogiite

TiO2
IMA status
  • Approved
IMA symbol
Aka
IMA approved
2008
Also known as
  • Akaogiiet
  • IMA2007-058

Where it forms, where it's found

Geological setting

Heavily shocked garnet-cordierite-sillimanite gneiss in a meteorite impact crater.

Type locality
Seelbronn Quarry
  1. Amerdingen
  2. Donau-Ries District
  3. Swabia
  4. Bavaria
  5. Germany

48.7225°, 10.4886°

4recorded occurrences
Source · OpenStreetMap

Optical

Internal reflections
Intense, royal blue internal reflections.
Notes

The intense royal blue internal reflections are a distinguishing feature, in contrast to the white internal reflections of rutile and to the brown to pink internal reflections of TiO2-II, respectively.

Crystallography

Crystal system
Monoclinic
Space group
P1 21/c 1
Cell parameters
a = 4.606 Å · b = 4.986 Å · c = 4.933 Å
Cell angles
β = 99.17 °
Ratio a:b:c
1 : 1.083 : 1.071
Type-locality form

Grains consisting of countless randomly oriented submicrometer particles. Optically distinguishable from rutile only in reflected light microscopy, through its slightly higher brightness and the intense royal blue color of its internal reflections in crossed nicols.

Chemical composition

Constituent elements
Mass composition breakdown
ElementAtoms At. mass g/mol Mass g/molMass share
22TiTitaniumTitanium147.86747.867
59.93%
8OOxygenOxygen215.99931.998
40.07%
Total79.865100.00%

Mass share = atoms × atomic mass ÷ molar mass × 100

From IMA formula

Synonyms

  • Akaogiiet
  • IMA2007-058

In other languages

German
Akaogiit · IMA 2007-058
Spanish
Akaogiíta
Italian
akaogiite
Chinese
赤荻石
Russian
Акаогиит

Classification

Strunz
10th ed.

4.D0

  • 4OxidesClass
  • 4.DMetal: Oxygen = 1:2 and similarDivision
  • 4.D0— unnamed intermediate level —Group
  • 4.D0AkaogiiteSpecies

Group, growth & confusion

In the same group
1 members
Commonly confused with
4 minerals

Literature, links & citation

Citations
  1. 2010El Goresy, A., Dubrovinsky, L.S., Gillet, P., Graup, G., Chen, M. (2010) Akaogiite: An ultra-dense polymorph of TiO2 with seven-coordinated titanium, in shocked garnet gneisses from the Ries Crater, Germany. American Mineralogist: 95: 892-895.
  2. 2016www.typmineral.uni-hamburg.de (n.d.) http://www.typmineral.uni-hamburg.de/tables/en/akaogiite.html
  3. 2021(2021) Akaogiite. Handbook of Mineralogy. Mineralogical Society of America
Cite this entry
@misc{mineral2026,
  author    = {Mineral Index editorial board},
  title     = {Akaogiite — Mineral Index},
  year      = {2026},
  url       = {https://mineralindex.org/minerals/akaogiite-35912},
  note      = {Accessed 2026-05-11}
}