Proxidecagonite

Al34Ni9Fe2
IMA status
  • Approved
IMA symbol
Pdec
IMA approved
2018
Also known as
  • IMA2018-038
  • Proxidecagoniet

Where it forms, where it's found

Geological setting

Meteoritic fragments of the Khatyrka meteorite.

Type locality
Khatyrka meteorite
  1. Iomrautvaam massif
  2. Anadyrsky District
  3. Chukotka Autonomous Okrug
  4. Russia

62.6531°, 174.5006°

1recorded occurrences
Source · OpenStreetMap

Physical

Colour
Grey to black
Streak
Black

Optical

Pleochroism
Non-pleochroic
Anisotropism
Without characteristic rotation-tints.
Bireflectance
Weak to moderate
Internal reflections
Absent
Tropism
Anisotropic
Reflectance R%
(28.8,31.2) 471.1, (29.4,32.0) 548.3, (30.6,32.8) 586.6, (31.5,33.7) 652.3
Reflected-light panel
R̄ 30.1 %anisotropic · dual curve
Specimen sRGB 202, 137, 73
White reference100 % reflector under same lamp
R₁ R₂
Mode
Bireflectance
Weak to moderate
Anisotropism
Without characteristic rotation-tints.
Internal reflections
Absent

Crystallography

Crystal system
Orthorhombic
Space group
Pnma
Cell parameters
a = 29.013(3) Å · b = 8.156(1) Å · c = 12.401(2) Å
Ratio a:b:c
1 : 0.281 : 0.427
Unit cell volume
2934.4 ų
Z
4
Type-locality form

20 µm anhedral grain.

Chemical composition

Constituent elements
Mass composition breakdown
ElementAtoms At. mass g/mol Mass g/molMass share
13AlAluminiumAluminium3426.982917.388
58.91%
28NiNickelNickel958.693528.237
33.92%
26FeIronIron255.845111.690
7.17%
Total1557.315100.00%

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

From IMA formula

Synonyms

  • IMA2018-038
  • Proxidecagoniet

In other languages

German
IMA 2018-038 · Proxidecagonit

Classification

Strunz
10th ed.

1.AA.50

  • 1ElementsClass
  • 1.AMetals and Intermetallic AlloysDivision
  • 1.AACopper-cupalite familyGroup
  • 1.AA.50ProxidecagoniteSpecies

Literature, links & citation

Citations
  1. 2018Hålenius, U., Hatert, F., Pasero, M., Mills, S. J. (2018) CNMNC Newsletter No. 44, New minerals and nomenclature modifications approved in 2018. Mineralogical Magazine, 82 (4) 1015-1021 doi:10.1180/mgm.2018.148DOI: 10.1180/mgm.2018.148
  2. 2018Bindi, Luca; Pham, Joyce; Steinhardt, Paul J. (2018) Previously unknown quasicrystal periodic approximant found in space. Scientific Reports, 8. 16271 doi:10.1038/s41598-018-34375-xDOI: 10.1038/s41598-018-34375-x
  3. 2020Belakovskiy, Dmitriy I.; Uvarova, Yulia; Cámara, Fernando (2020) New Mineral Names. American Mineralogist, 105 (12). 1920-1925 doi:10.2138/am-2020-NMN1051227DOI: 10.2138/am-2020-NMN1051227
  4. 2021(2021) Proxidecagonite. Handbook of Mineralogy. Mineralogical Society of America
Cite this entry
@misc{mineral2026,
  author    = {Mineral Index editorial board},
  title     = {Proxidecagonite — Mineral Index},
  year      = {2026},
  url       = {https://mineralindex.org/minerals/proxidecagonite-53058},
  note      = {Accessed 2026-05-11}
}