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Uraninite

A valid IMA mineral species - grandfathered
This page kindly sponsored by Aaron "Van" Van Alstine
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About UraniniteHide

Formula:
UO2
Colour:
Black, brownish-black, greyish, greenish; green-gray (thin fragments)
Lustre:
Greasy, Sub-Metallic, Dull
Hardness:
5 - 6
Specific Gravity:
10.63 - 10.95
Crystal System:
Isometric
Member of:
Name:
Originally recognized before the element uranium was known and called "schwarz beck-erz" by Franz Ernst Brückmann in 1727. Subsequently described with several names, including "pseudogalena" and "pitch-like zinc-blende" by Johan Gottschalk Wallerius (Vallerius) in 1747. Named pechblende by Axel Cronstedt in 1758. Named "uranerz" by Martin Klaproth after he discovered the element uranium in this mineral. Many spelling variations of the above-mentioned names are known. Renamed in 1845 by Wilhelm Karl von Haidinger for its composition containing uranium.
Uraninite Group. Thorianite-Uraninite Series.

Occurs in granitic and syenitic pegmatites. Colloform crusts in high-temperature hydrothermal veins. In quartz-pebble conglomerates.

Typical uranium ore contains ca. 0.1 mg of Po / metric ton; Ra is more abundant, by 0.14 g of Ra / metric ton; 231Pa is present in a very tiny amount, usually as low as 0.1 ppm, but may reach 3 ppm; traces of Np (isotopes with masses from 237 to 240) and 238Pu are also detectable. Kenna & Kuroda (1964) report values as low as 2.5–3.1 × 10−10 g of technetium (99Tc) per kg of African material. Traces of Cm are possible, but have not yet been detected.

Compare 'UM1978-10-O:U'.


Unique IdentifiersHide

Mindat ID:
4102
Long-form identifier:
mindat:1:1:4102:3

IMA Classification of UraniniteHide

Approved, 'Grandfathered' (first described prior to 1959)

Classification of UraniniteHide

4.DL.05

4 : OXIDES (Hydroxides, V[5,6] vanadates, arsenites, antimonites, bismuthites, sulfites, selenites, tellurites, iodates)
D : Metal: Oxygen = 1:2 and similar
L : With large (+- medium-sized) cations; fluorite-type structures
5.1.1.1

5 : OXIDES CONTAINING URANIUM OR THORIUM
1 : AXO2·xH2O
7.16.1

7 : Oxides and Hydroxides
16 : Oxides of U

Mineral SymbolsHide

As of 2021 there are now IMA–CNMNC approved mineral symbols (abbreviations) for each mineral species, useful for tables and diagrams.

Please only use the official IMA–CNMNC symbol. Older variants are listed for historical use only.

SymbolSourceReference
UrnIMA–CNMNCWarr, L.N. (2021). IMA–CNMNC approved mineral symbols. Mineralogical Magazine, 85(3), 291-320. doi:10.1180/mgm.2021.43
UrnWhitney & Evans (2010)Whitney, D.L. and Evans, B.W. (2010) Abbreviations for names of rock-forming minerals. American Mineralogist, 95, 185–187 doi:10.2138/am.2010.3371
UrnThe Canadian Mineralogist (2019)The Canadian Mineralogist (2019) The Canadian Mineralogist list of symbols for rock- and ore-forming minerals (December 30, 2019). download

Pronunciation of UraniniteHide

Pronunciation:
PlayRecorded byCountry
Jolyon RalphUnited Kingdom

Physical Properties of UraniniteHide

Greasy, Sub-Metallic, Dull
Transparency:
Opaque
Colour:
Black, brownish-black, greyish, greenish; green-gray (thin fragments)
Streak:
Brownish black, grayish, olive-green
Hardness:
5 - 6 on Mohs scale
Hardness:
VHN50=499 - 548 kg/mm2 - Vickers
Tenacity:
Brittle
Fracture:
Irregular/Uneven, Conchoidal
Density:
10.63 - 10.95 g/cm3 (Measured)    10.88 g/cm3 (Calculated)
Comment:
Decreasing with oxidation to low as 6.5

Optical Data of UraniniteHide

Type:
Isotropic
Reflectivity:
WavelengthR1 (%)
400nm17.6%
420nm17.3%
440nm17.0%
460nm16.8%
480nm16.5%
500nm16.3%
520nm16.2%
540nm16.0%
560nm15.9%
580nm15.8%
600nm15.9%
620nm15.9%
640nm16.0%
660nm16.0%
680nm16.1%
700nm16.2%


Graph shows reflectance levels at different wavelengths (in nm). Peak reflectance is 17.6%.
Colour in reflected light:
Light grey with brownish tint
Internal Reflections:
Dark brown

Chemistry of UraniniteHide

Mindat Formula:
UO2
Element Weights:
Element% weight
U88.150 %
O11.850 %

Calculated from ideal end-member formula.
CAS Registry number:
1344-57-6

CAS Registry numbers are published by the American Chemical Society
Common Impurities:
Th,Zr,Pb,Ra,Ac,Po,Ce,Y,Er,La

Age distributionHide

Recorded ages:
Paleoproterozoic to Jurassic : 1738 ± 18 Ma to 152 ± 1 Ma - based on 148 recorded ages.

Crystallography of UraniniteHide

Crystal System:
Isometric
Class (H-M):
m3m (4/m 3 2/m) - Hexoctahedral
Space Group:
Fm3m
Cell Parameters:
a = 5.4682 Å
Unit Cell V:
163.51 ų (Calculated from Unit Cell)
Z:
4
Morphology:
Octahedral, cubooctahedral, and cubic crystals; dodecahedrons less common. Massive, botryoidal, reniform, banded, columnar, curved lamellar.
Twinning:
On {111}, rare.
Comment:
Synthetic material UO2.03

Crystal StructureHide

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IDSpeciesReferenceLinkYearLocalityPressure (GPa)Temp (K)
0011728UraniniteWyckoff R W G (1963) Second edition. Interscience Publishers, New York, New York Fluorite structure Crystal Structures 1 239-44419630293
CIF Raw Data - click here to close

X-Ray Powder DiffractionHide

Powder Diffraction Data:
d-spacingIntensity
3.157 Å(100)
1.934 Å(49)
2.735 Å(48)
1.649 Å(47)
1.255 Å(18)
1.223 Å(15)
1.0523 Å(15)
Comments:
Synthetic.

Geological EnvironmentHide

Paragenetic Mode(s):
Paragenetic ModeEarliest Age (Ga)
Near-surface Processes
26 : Hadean detrital minerals
Stage 4b: Highly evolved igneous rocks>3.0
34 : Complex granite pegmatites
35 : Ultra-alkali and agpaitic igneous rocks
Stage 10a: Neoproterozoic oxygenation/terrestrial biosphere<0.6
49 : Oxic cellular biomineralization (see also #44)<0.54
50 : Coal and/or oil shale minerals<0.36
53 : Other minerals with taphonomic origins<0.4
Stage 10b: Anthropogenic minerals<10 Ka
54 : Coal and other mine fire minerals (see also #51 and #56)

Type Occurrence of UraniniteHide

Synonyms of UraniniteHide

Other Language Names for UraniniteHide

Varieties of UraniniteHide

ArsenuranArsenoan uraninite
CleveiteA REE-and Th-bearing variety of uraninite. Presence of (Y, Ce, etc.)2O3 extends to at least 10%. Related to bröggerite.

The first portions of terrestrial Helium (He) were obtained during Cleveite dissolution in sulfuric acid (Ramsey, 23 March 1895–27 ...
NiveniteA REE-bearing variety of uraninite. Presence of (Y,Ce,etc.)2O3 extends to at least 10%.
PitchblendeA massive, often globular, possibly impure, variety of Uraninite.
Thorian UraniniteTh-bearing variety of uraninite.

First described in the late 19th century from Ånnerud (Ånnerød), Moss, Østfold, Norway.
Uranoniobite (of Hermann)A crystalline variety previously thought to contain Nb

Relationship of Uraninite to other SpeciesHide

Member of:
Other Members of Uraninite Group:
Cerianite-(Ce)(Ce4+,Th)O2Iso. m3m (4/m 3 2/m) : Fm3m
ThorianiteThO2Iso. m3m (4/m 3 2/m) : Fm3m
Forms a series with:

Common AssociatesHide

Associated Minerals Based on Photo Data:
184 photos of Uraninite associated with UranophaneCa(UO2)2(SiO3OH)2 · 5H2O
135 photos of Uraninite associated with Gummite
105 photos of Uraninite associated with QuartzSiO2
98 photos of Uraninite associated with MuscoviteKAl2(AlSi3O10)(OH)2
75 photos of Uraninite associated with AlbiteNa(AlSi3O8)
74 photos of Uraninite associated with CalciteCaCO3
59 photos of Uraninite associated with FluoriteCaF2
59 photos of Uraninite associated with ZirconZr(SiO4)
57 photos of Uraninite associated with Sandstone
57 photos of Uraninite associated with Native GoldAu

Related Minerals - Strunz-mindat GroupingHide

4.DL.Xianhuaite-(Ce)K2CeNb5O15Tet. 4/mmm (4/m 2/m 2/m) : P4/mbm
4.DL.05Aeschynite GroupAD2O6
4.DL.05Zirkelite(Ti,Ca,Zr)O2-xIso.
4.DL.05ThorianiteThO2Iso. m3m (4/m 3 2/m) : Fm3m
4.DL.05Cerianite-(Ce)(Ce4+,Th)O2Iso. m3m (4/m 3 2/m) : Fm3m
4.DL.10Tazheranite(Zr,Ti,Ca)(O,◻)2Iso. m3m (4/m 3 2/m)
4.DL.10HiärneiteCa2Zr4Mn3+SbTiO16Tet. 4/mmm (4/m 2/m 2/m) : I41/acd
4.DL.10CalzirtiteCa2Zr5Ti2O16Tet. 4/mmm (4/m 2/m 2/m) : I41/acd
4.DL.15VorlaniteCa(U6+)O4Iso. m3m (4/m 3 2/m) : Fm3m

RadioactivityHide

Radioactivity:
Element % Content Activity (Bq/kg) Radiation Type
Uranium (U) 88.1498% 22,037,450 α, β, γ
Thorium (Th) 0.0000% 0 α, β, γ
Potassium (K) 0.0000% 0 β, γ

For comparison:

  • Banana: ~15 Bq per fruit
  • Granite: 1,000–3,000 Bq/kg
  • EU exemption limit: 10,000 Bq/kg

Note: Risk is shown relative to daily recommended maximum exposure to non-background radiation of 1000 µSv/year. Note that natural background radiation averages around 2400 µSv/year so in reality these risks are probably extremely overstated! With infrequent handling and safe storage natural radioactive minerals do not usually pose much risk.

Interactive Simulator:

Note: The mass selector refers to the mass of radioactive mineral present, not the full specimen, also be aware that the matrix may also be radioactive, possibly more radioactive than this mineral!

Activity:

DistanceDose rateRisk
1 cm
10 cm
1 m

The external dose rate (D) from a radioactive mineral is estimated by summing the gamma radiation contributions from its Uranium, Thorium, and Potassium content, disregarding daughter-product which may have a significant effect in some cases (eg 'pitchblende'). This involves multiplying the activity (A, in Bq) of each element by its specific gamma ray constant (Γ), which accounts for its unique gamma emissions. The total unshielded dose at 1 cm is then scaled by the square of the distance (r, in cm) and multiplied by a shielding factor (μshield). This calculation provides a 'worst-case' or 'maximum risk' estimate because it assumes the sample is a point source and entirely neglects any self-shielding where radiation is absorbed within the mineral itself, meaning actual doses will typically be lower. The resulting dose rate (D) is expressed in microsieverts per hour (μSv/h).

D = ((AU × ΓU) + (ATh × ΓTh) + (AK × ΓK)) / r2 × μshield

Fluorescence of UraniniteHide

Other InformationHide

Health Risks:
Contains uranium - always wash hands after handling. Avoid inhaling dust when handling or breaking. Never lick or ingest. Avoid prolonged exposure in the proximity of the body. Store away from inhabited areas.

Internet Links for UraniniteHide

References for UraniniteHide

Reference List:

Localities for UraniniteHide

This map shows a selection of localities that have latitude and longitude coordinates recorded. Click on the symbol to view information about a locality. The symbol next to localities in the list can be used to jump to that position on the map.

Locality ListShow

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