Magnioursilite

Mg4(UO2)4(Si2O5)5(OH)6 · 20H2O
IMA status
  • Approved
  • Grandfathered
IMA symbol
Mau
Also known as
  • Magnioursiliet

Where it forms, where it's found

Geological setting

Occurs along joints in granite porphyry.

Type locality
Oktyabr'skoye U Deposit
  1. Kyzyltyube-Sai
  2. Khodzhent (Leninabad)
  3. Sughd
  4. Tajikistan
1recorded occurrences
Source · OpenStreetMap

Radioactivity

Physical

Hardness
123456789103/ 10 MOHS
  1. 1Talc
  2. 2Gypsum
  3. 3Calcite
  4. 4Fluorite
  5. 5Apatite
  6. 6Orthoclase
  7. 7Quartz
  8. 8Topaz
  9. 9Corundum
  10. 10Diamond
Colour
Lemon-yellow
Tenacity
brittle
Density
3.254 g/cm³

Optical

Pleochroism
Weak

X = pale green; Z = green.

Extinction
Parallel. Elongation positive.
UV response
Fluorescent in greenish yellow under ultraviolet light.

Crystallography

Type-locality form

Lemon-yellow earthy or nodular incrustations, rarely radiating spherulites.

Comment

Poorly defined crystallography

Chemical composition

Constituent elements
Mass composition breakdown
ElementAtoms At. mass g/mol Mass g/molMass share
92UUraniumUranium4238.029952.116
41.03%
8OOxygenOxygen5915.999943.941
40.68%
14SiSiliconSilicon1028.085280.850
12.10%
12MgMagnesiumMagnesium424.30597.220
4.19%
1HHydrogenHydrogen461.00846.368
2.00%
Total2320.495100.00%

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

From IMA formula

Synonyms

  • Magnioursiliet

In other languages

German
Magnioursilit
Italian
magnioursilite

Classification

Strunz
10th ed.

9.AK.35

  • 9SilicatesClass
  • 9.ANesosilicatesDivision
  • 9.AKUranyl neso- and polysilicatesGroup
  • 9.AK.35MagnioursiliteSpecies

Literature, links & citation

Citations
  1. 1957Chernikov A A, Krutetskaya O V, Sidelnikova V D (1957): Ursilite - a new silicate of uranium. Atomnaya Energiya Voprosy Geologii Urana, Supplement 6, 73-77 (in Russian).
  2. 1958Proc. 2nd U.N. Int. Conf. on the Peaceful Uses of Atomic Energy, 2: 298-299 (1958)
  3. 1959Proc. 2nd U.N. Int. Conf. on the Peaceful Uses of Atomic Energy, 3, 174-177 (1959)
  4. 1977Chernikov, A.A., Sidorenko, G.A., Valueva, A.A. (1977) New data on uranyl minerals of the ursilite-weeksite group (in Russian). Zapiski Vsesoyuznogo Mineralogicheskogo Obshchestva, 106(5), 553-564.
  5. 2018Hålenius, U., Hatert, F., Pasero, M., Mills, S. J. (2018) CNMNC Newsletter No 43, New minerals and nomenclature modifications approved in 2018. Mineralogical Magazine, 82 (3) 779-785 doi:10.1180/mgm.2018.72DOI: 10.1180/mgm.2018.72
Cite this entry
@misc{mineral2026,
  author    = {Mineral Index editorial board},
  title     = {Magnioursilite — Mineral Index},
  year      = {2026},
  url       = {https://mineralindex.org/minerals/magnioursilite-11332},
  note      = {Accessed 2026-05-11}
}