Metacalciouranoite

(Ca,Na,Ba)U2O7 · 2H2O
IMA status
  • Approved
IMA symbol
Mcu
Discovered
1973
Also known as
  • IMA1971-054
  • Metacalciouranoiet

Where it forms, where it's found

Type locality
Oktyabr'skoe Mo-U Deposit
  1. Strel'tsovskoe Mo-U ore field
  2. Krasnokamensk
  3. Krasnokamensky District
  4. Zabaykalsky Krai
  5. Russia

50.0918°, 118.2496°

1recorded occurrences
Source · OpenStreetMap

Radioactivity

Physical

Transparency
Transparent
Colour
Orange
Density
4.90 g/cm³

Optical

Optical type
Biaxial (+) · 2V measured = 81° · 2V calc = 80°
Refractive index
1.897 – 1.932
Surface relief
Very high
Principal indices
nα 1.897 · nβ 1.911 · nγ 1.932
Dispersion
r > v extreme
Michel-Lévy diagramhighlighted lineδ = 0.0350
Attainable Michel-Lévy rangeΔ ∈ [0, t·δmax]350 nm1st order
Δ = 0Δmax
Thin-section mosaic70 grains · random 3D orientations
PPLpleochroism per grain
XPLindependent extinctions · rotate the stage
Interference simulatorsingle grain · PPL ↔ XPL
PPLpleochroism only · colour blends on rotation
XPLinterference colour · extinct every 90°
Retardation350 nm
Order1st order
XPL colour

Crystallography

Type-locality form

dense, fine-grained aggregate

Comment

Crystal Data: n.d. Point Group: n.d; Space Group: n.d. Z == n.d

Chemical composition

Constituent elements
Mass composition breakdown
ElementAtoms At. mass g/mol Mass g/molMass share
92UUraniumUranium2238.029476.058
57.74%
8OOxygenOxygen915.999143.991
17.46%
56BaBariumBarium1137.327137.327
16.66%
20CaCalciumCalcium140.07840.078
4.86%
11NaSodiumSodium122.99022.990
2.79%
1HHydrogenHydrogen41.0084.032
0.49%
Total824.476100.00%

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

From IMA formula

Synonyms

  • IMA1971-054
  • Metacalciouranoiet

In other languages

German
IMA 1971-054 · Metacalciouranoit
Italian
Metacalciouranoite

Classification

Strunz
10th ed.

4.GB.20

  • 4OxidesClass
  • 4.GUranyl HydroxidesDivision
  • 4.GBWith additional cations (K, Ca, Ba, Pb, etc.); with mainly UO2(O,OH)5 pentagonal polyhedraGroup
  • 4.GB.20MetacalciouranoiteSpecies
Dana
8th ed.

05.04.03.01

  • 05Oxides Containing Uranium or ThoriumClass
  • 05.04AX2O7·xH2OType
  • 05.04.03— unnamed intermediate level —Group
  • 05.04.03.01MetacalciouranoiteSpecies
CIM

7.16.17

  • 7Oxides and HydroxidesClass
  • 7.16Oxides of UGroup
  • 7.16.17MetacalciouranoiteSpecies

Literature, links & citation

Citations
  1. 1973Fleischer, Michael (1973) New mineral names. American Mineralogist, 58 (11-12) 1111-1115
  2. 1973Rogova, V.P., Belova, L.N., Kiziyarov, G.N., Kuznetsova, N.N. (1973) Bauranoite and metacaltsuranoite [metacalciouranoite] - new minerals of the group of hydrous uranium oxides. Zapiski Vsesoyuznogo Mineralogicheskogo Obshchestva: 102(1): 75-81.
  3. 1985Belova, L.N., Ryzhov, B.I., Fedorov, O.V., Lyubomilova, G.V. (1985) Typomorphism and isomorphism of the wölsendorfite group of uranium hydroxides. Izvestiya Akademii Nauk SSSR, Seriya Geologicheskaya: 1985(2): 65-72.
  4. 2007(2007) Metacalciouranoite. Handbook of Mineralogy. Mineralogical Society of America
Cite this entry
@misc{mineral2026,
  author    = {Mineral Index editorial board},
  title     = {Metacalciouranoite — Mineral Index},
  year      = {2026},
  url       = {https://mineralindex.org/minerals/metacalciouranoite-2669},
  note      = {Accessed 2026-05-11}
}