Hydronováčekite

Mg(UO2)2(AsO4)2 · 12H2O
IMA status
  • Approved
  • Grandfathered
IMA symbol
Nvč-I
Also known as
  • Hydronováčekiet
  • Novacikit

Where it forms, where it's found

Type locality
Walpurgis Flacher vein
  1. Weißer Hirsch Mine (shaft 3)
  2. Neustädtel
  3. Schneeberg
  4. Erzgebirgskreis
  5. Saxony
  6. Germany

50.5883°, 12.6389°

46recorded occurrences
Source · OpenStreetMap

Radioactivity

Physical

Hardness
123456789102.5/ 10 MOHS
  1. 1Talc
  2. 2Gypsum
  3. 3Calcite
  4. 4Fluorite
  5. 5Apatite
  6. 6Orthoclase
  7. 7Quartz
  8. 8Topaz
  9. 9Corundum
  10. 10Diamond
Transparency
Transparent
Colour
Light yellow · straw yellow
Streak
White, pale yellow
Cleavage
Perfect

Perfect on (001), good on (100) and (010). Less pronounced than the lower hydration levels (i.e. nováčekite and metanováčekite).

Optical

Optical type
Uniaxial (-)
Refractive index
1.62 – 1.641
Surface relief
Moderate
Principal indices
nω 1.62 – 1.641 · nε 1.62 – 1.625
Notes

Symmetry requires pseudo-uniaxial optical character.

Michel-Lévy diagramhighlighted lineδ = 0.0080
Attainable Michel-Lévy rangeΔ ∈ [0, t·δmax]80 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°
Retardation80 nm
Order1st order
XPL colour

Crystallography

Crystal system
Triclinic
Space group
#2
Cell parameters
a = 7.1594 Å · b = 7.161 Å · c = 11.3146 Å
Cell angles
α = 81.391 ° · β = 81.177 ° · γ = 88.884 °
Ratio a:b:c
1 : 1.000 : 1.580
Comment

Pseudo-tetragonal (long axis ~22 A).

Crystal structure

Chemical composition

Constituent elements
Mass composition breakdown
ElementAtoms At. mass g/mol Mass g/molMass share
92UUraniumUranium2238.029476.058
44.98%
8OOxygenOxygen2415.999383.976
36.28%
33AsArsenicArsenic274.922149.844
14.16%
12MgMagnesiumMagnesium124.30524.305
2.30%
1HHydrogenHydrogen241.00824.192
2.28%
Total1058.375100.00%

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

From IMA formula

Synonyms

  • Hydronováčekiet
  • Novacikit

In other languages

French
Nováčekite-I
German
Hydronováčekit · Novacekit · Nováčekit-I
Spanish
Novacekita
Italian
idronováčekite · Novacekite · Nováčekite I

Classification

Strunz
10th ed.

8.EB.05

  • 8Phosphates, Arsenates, VanadatesClass
  • 8.EUranyl phosphates and arsenatesDivision
  • 8.EBUO2:RO4 = 1:1Group
  • 8.EB.05HydronováčekiteSpecies
Dana
8th ed.

40.2a.10.01

  • 40Hydrated Normal Phosphates, Arsenates and VanadatesClass
  • 40.2aAB2(XO4)2·xH2O, containing (UO2)2+Type
  • 40.2a.10— unnamed intermediate level —Group
  • 40.2a.10.01HydronováčekiteSpecies
CIM

20.7.7

  • 20Arsenates (also arsenates with phosphate, but without other anions)Class
  • 20.7Arsenates of UGroup
  • 20.7.7HydronováčekiteSpecies

Group, growth & confusion

Literature, links & citation

Citations
  1. 1951Frondel, Clifford (1951) Studies of uranium minerals (IX): Saléeite and novacekite. American Mineralogist, 36 (9-10) 680-686
  2. 1954Stern, T. W., Annell, C. S. (1954) A second locality of novacekite. American Mineralogist, 39 (7-8) 675-676
  3. 1956Huang, W. T. (1956) Novacekite from the Wichita Mountains, Oklahoma. American Mineralogist, 41 (1-2) 152-153
  4. 1961Walenta, K., Wimmenauer, W. (1961) Der Mineralbestand des Michaelganges im Weiler bei Lahr (Schwarzwald). Jahreshefte des Geologischen Landesamts Baden-Württemberg: 4: 7-37 (in German).
  5. 1964Walenta, Kurt, Walenta, Kurt (1964) Beiträge zur Kenntnis seltener Arsenatmineralien unter besonderer Berücksichtigung von Vorkommen des Schwarzwaldes. 1. Folge. [Rare arsenate minerals with special consideration of occurrences in the Black Forest. Part I]. Tschermaks Mineralogische und Petrographische Mitteilungen, 9 (1). 111-174 doi:10.1007/bf01127780DOI: 10.1007/bf01127780
Cite this entry
@misc{mineral2026,
  author    = {Mineral Index editorial board},
  title     = {Hydronováčekite — Mineral Index},
  year      = {2026},
  url       = {https://mineralindex.org/minerals/hydronovacekite-2937},
  note      = {Accessed 2026-05-11}
}