Ningyoite

(U,Ca,Ce)2(PO4)2 · 1-2H2O
IMA status
  • Approved
IMA symbol
Nin
Also known as
  • Ningyoiet

Where it forms, where it's found

Geological setting

Black uranium ores in conglomerate

Type locality
Ningyo-toge mine
  1. Tottori Prefecture
  2. Japan

35.3083°, 133.9228°

25recorded occurrences
Source · OpenStreetMap

Radioactivity

Physical

Hardness
123456789103 – 4/ 10 MOHS
  1. 1Talc
  2. 2Gypsum
  3. 3Calcite
  4. 4Fluorite
  5. 5Apatite
  6. 6Orthoclase
  7. 7Quartz
  8. 8Topaz
  9. 9Corundum
  10. 10Diamond
Colour
Brownish green to brown

Optical

Optical type
Biaxial
Refractive index
1.64 – 1.71
Surface relief
High
Principal indices
nα 1.69 – 1.70 · nβ 1.64 – 1.71
Pleochroism
Weak

Paler in X direction

Dispersion
not discernible

Crystallography

Crystal system
Orthorhombic
Cell parameters
a = 6.78 Å · b = 12.1 Å · c = 6.38 Å
Ratio a:b:c
1 : 1.785 : 0.941
Type-locality form

Unoxidized zone, usually as a thin coating on pyrite and apatite or filling cavities in the conglomerate.

Comment

May be hexagonal or trigonal (see Scharmová & Scharm (1994) and references cited therein).

Chemical composition

Constituent elements
Mass composition breakdown
ElementAtoms At. mass g/mol Mass g/molMass share
92UUraniumUranium2238.029476.058
45.58%
58CeCeriumCerium2140.116280.232
26.83%
8OOxygenOxygen915.999143.991
13.79%
20CaCalciumCalcium240.07880.156
7.68%
15PPhosphorusPhosphorus230.97461.948
5.93%
1HHydrogenHydrogen21.0082.016
0.19%
Total1044.401100.00%

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

From IMA formula

Synonyms

  • Ningyoiet

In other languages

German
Ningyoit
Italian
Ningyoite
Japanese
人形石

Classification

Strunz
10th ed.

8.CJ.85

  • 8Phosphates, Arsenates, VanadatesClass
  • 8.CPhosphates without additional anions, with H2ODivision
  • 8.CJWith only large cationsGroup
  • 8.CJ.85NingyoiteSpecies
Dana
8th ed.

40.04.08.01

  • 40Hydrated Normal Phosphates, Arsenates and VanadatesClass
  • 40.04(AB)5(XO4)2·xH2OType
  • 40.04.08Ningyoite GroupGroup
  • 40.04.08.01NingyoiteSpecies
CIM

19.11.13

  • 19PhosphatesClass
  • 19.11Phosphates of UGroup
  • 19.11.13NingyoiteSpecies

Literature, links & citation

Citations
  1. 1959Muto, T., Meyrowitz, R., Pommer, A. M., Murano, T. (1959) Ningyoite, a new uranous phosphate from Japan. American Mineralogist, 44 (5-6) 633-650
  2. 1960Fleischer, M.; Chao, E.C.T. (1960) New mineral names. American Mineralogist, 45 (5-6). 753-756
  3. 1962MUTO, TADASHI (1962) The precipitation environment of ningyoite. Mineralogical Journal, 3 (5). 306-337 doi:10.2465/minerj1953.3.306 DOI: 10.2465/minerj1953.3.306
  4. 1965MUTO, TADASHI (1965) Thermochemical stability of ningyoite. Mineralogical Journal, 4 (4). 245-274 doi:10.2465/minerj1953.4.245 DOI: 10.2465/minerj1953.4.245
  5. 1970Kajitani, Kei (1970) A geochemical study on the genesis of ningyoite the special calcium uranous phosphate mineral. Economic Geology, 65 (4) 470-480 doi:10.2113/gsecongeo.65.4.470DOI: 10.2113/gsecongeo.65.4.470
Cite this entry
@misc{mineral2026,
  author    = {Mineral Index editorial board},
  title     = {Ningyoite — Mineral Index},
  year      = {2026},
  url       = {https://mineralindex.org/minerals/ningyoite-2906},
  note      = {Accessed 2026-05-11}
}