Ewingite

Mg8Ca8(UO2)24(CO3)30O4(OH)12(H2O)138
IMA status
  • Approved
IMA symbol
Ewg
IMA approved
2016
Also known as
  • IMA2016-012

Where it forms, where it's found

Geological setting

Efflorescence growing directly on weathered uraninite in the mining adit

Type locality
Svornost Mine
  1. Jáchymov
  2. Karlovy Vary District
  3. Karlovy Vary Region
  4. Czech Republic

50.3725°, 12.9114°

3recorded occurrences
Source · OpenStreetMap

Radioactivity

Physical

Colour
Golden yellow

Optical

Tropism
Anisotropic

Crystallography

Crystal system
Tetragonal
Space group
I41/acd
Cell parameters
a = 35.401(9) Å · c = 48.157(13) Å
Unit cell volume
59245 ų
Type-locality form

Ewingite forms aggregates of golden-yellow crystals as large as 0.2 mm in diameter

Chemical composition

Constituent elements
Mass composition breakdown
ElementAtoms At. mass g/mol Mass g/molMass share
92UUraniumUranium24238.0295712.696
49.46%
8OOxygenOxygen29215.9994671.708
40.45%
6CCarbonCarbon3012.011360.330
3.12%
20CaCalciumCalcium840.078320.624
2.78%
1HHydrogenHydrogen2881.008290.304
2.51%
12MgMagnesiumMagnesium824.305194.440
1.68%
Total11550.102100.00%

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

From IMA formula

Synonyms

  • IMA2016-012

In other languages

French
ewingite
German
Ewingit · IMA 2016-012

Classification

Strunz
10th ed.

5.EC.15

  • 5CarbonatesClass
  • 5.EUranyl CarbonatesDivision
  • 5.ECUO2:CO3 < 1:1 - 1:2Group
  • 5.EC.15EwingiteSpecies

Literature, links & citation

Citations
  1. 2016Hålenius, U., Hatert, F., Pasero, M., Mills, S. J. (2016) New minerals and nomenclature modifications approved in 2016, CNMNC Newsletter no 31. Mineralogical Magazine, 80 (4) 691-697 doi:10.1180/minmag.2016.080.083DOI: 10.1180/minmag.2016.080.083
  2. 2017Olds, T. A., Plášil, J., Kampf, A. R., Simonetti, A., Sadergaski, L. R., Chen, Y.-S. and Burns, P. C. (2017) Ewingite: Earth’s most complex mineral. Geology, 45, 11, 1007–1010.
  3. 2020(2020) Ewingite. Handbook of Mineralogy. Mineralogical Society of America
Cite this entry
@misc{mineral2026,
  author    = {Mineral Index editorial board},
  title     = {Ewingite — Mineral Index},
  year      = {2026},
  url       = {https://mineralindex.org/minerals/ewingite-47791},
  note      = {Accessed 2026-05-11}
}