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Natroaphthitalite

A valid IMA mineral species
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About NatroaphthitaliteHide

Formula:
KNa3(SO4)2
Colour:
yellow to colorless
Specific Gravity:
2.664 (Calculated)
Crystal System:
Trigonal
Name:
The sodium analogue of aphthitalite
Isostructural with:
Isostructural with aphthitalite and möhnite.


Unique IdentifiersHide

Mindat ID:
53216
Long-form identifier:
mindat:1:1:53216:1

IMA Classification of NatroaphthitaliteHide

Classification of NatroaphthitaliteHide

7.AC.35

7 : SULFATES (selenates, tellurates, chromates, molybdates, wolframates)
A : Sulfates (selenates, etc.) without additional anions, without H2O
C : With medium-sized and large cations

Mineral SymbolsHide

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

SymbolSourceReference for Standard
NattIMA–CNMNCWarr, L.N. (2021). IMA–CNMNC approved mineral symbols. Mineralogical Magazine, 85(3), 291-320. doi:10.1180/mgm.2021.43

Physical Properties of NatroaphthitaliteHide

Transparency:
Translucent
Colour:
Yellow to colorless
Density:
2.664 g/cm3 (Calculated)

Optical Data of NatroaphthitaliteHide

Type:
Uniaxial (+)
RI values:
nω = 1.488(2) nε = 1.490(2)
Max. Birefringence:
δ = 0.002
Based on recorded range of RI values above.

Interference Colours:
The colours simulate birefringence patterns seen in thin section under crossed polars. They do not take into account mineral colouration or opacity.

Michel-Levy Bar The default colours simulate the birefringence range for a 30 µm thin-section thickness. Adjust the slider to simulate a different thickness.

Grain Simulation You can rotate the grain simulation to show how this range might look as you rotated a sample under crossed polars. Each grain retains its interference colour (retardation) while its brightness falls to black at extinction and reaches a maximum between extinction positions.

Surface Relief:
Moderate (negative)
Relative to Canada balsam mounting medium (n ≈ 1.537).

This shows the grain boundary and Becke line effect under plane-polarised light, based on the contrast between this mineral's average refractive index and the mounting medium. It does not take into account mineral colouration.
In focus
Interference Figure:
This shows the idealized uniaxial interference figure - the conoscopic (convergent-light, Bertrand-lens-in) view, for a grain cut with the optic axis centred and vertical. The coloured rings are isochromatics, computed with the same physics as the Michel-Lévy bar above; the dark cross is the isogyre.

For a genuinely uniaxial mineral viewed this way, that cross stays perfectly stationary if you rotate the stage - unlike a biaxial mineral, where it splits apart on rotation. That invariance is itself the standard diagnostic test for telling uniaxial and biaxial minerals apart at the microscope.

Chemistry of NatroaphthitaliteHide

Mindat Formula:
KNa3(SO4)2
Element Weights:
Element% weight
O42.638 %
Na22.975 %
S21.363 %
K13.024 %

Calculated from ideal end-member formula.
O
Na
S
K

Crystallography of NatroaphthitaliteHide

Crystal System:
Trigonal
Class (H-M):
3m(32/m) - Hexagonal Scalenohedral
Space Group:
P3m1
Setting:
P3m1
Cell Parameters:
a = 5.6014(3) Å, c = 7.1507(5) Å
Ratio:
a:c = 1 : 1.277
Unit Cell V:
194.30 ų (Calculated from Unit Cell)
Z:
1

X-Ray Powder DiffractionHide

Geological EnvironmentHide

Paragenetic Mode(s):
Paragenetic ModeEarliest Age (Ga)
Stage 7: Great Oxidation Event<2.4
45a : [Sulfates, arsenates, selenates, antimonates]

Type Occurrence of NatroaphthitaliteHide

General Appearance of Type Material:
single-crystal individuals up to 1 cm in diameter, sometimes combined in crusts up to 2 cm across, and as aqua-transparent colorless tabular to lamellar hexagonal crystals up to 2 mm across, sometimes skeletal, typically combined in parallel intergrowths
Place of Conservation of Type Material:
Type material is deposited in the collections of the Fersman Mineralogical Museum, Russian Academy of Sciences, Leninskiy Prospekt 18-2, Moscow 119071, Russia, registration number 5254/1
Associated Minerals at Type Locality:

Synonyms of NatroaphthitaliteHide

Other Language Names for NatroaphthitaliteHide

Related Minerals - Strunz-mindat GroupingHide

7.AC.Aluminopyracmonite(NH4)3Al(SO4)3Trig. 3 : R3
7.AC.AmgaiteTl+32Te6+O6Trig. 32 : P321
7.AC.05VanthoffiteNa6Mg(SO4)4Mon. 2/m : P21/b
7.AC.08Pyracmonite(NH4)3Fe(SO4)3Trig. 3m : R3c
7.AC.10LangbeiniteK2Mg2(SO4)3Iso. 23 : P213
7.AC.10Efremovite(NH4)2Mg2(SO4)3Iso. 23 : P213
7.AC.10Ferroefremovite(NH4)2Fe2+2(SO4)3Iso. 23 : P213
7.AC.10ManganolangbeiniteK2Mn2(SO4)3Iso. 23 : P213
7.AC.15YavapaiiteKFe3+(S6+O4)2Mon. 2/m : B2/m
7.AC.15EldfelliteNaFe3+(SO4)2Mon. 2/m : B2/m
7.AC.20Sabieite(NH4)Fe3+(SO4)2Trig. 32 : P321
7.AC.20Godovikovite(NH4)Al(SO4)2Trig. 32 : P321
7.AC.20StekliteKAl(SO4)2Trig. 32 : P321
7.AC.35AphthitaliteK3Na(SO4)2Trig. 3m(32/m) : P3m1
7.AC.35BelomarinaiteKNa(SO4)Trig. 3m : P31m
7.AC.35Möhnite(NH4)K2Na(SO4)2Trig. 3m : P3m1
7.AC.40ItelmeniteNa4Mg3Cu3(SO4)8Orth. mmm(2/m2/m2/m) : Pbca
7.AC.45SaranchinaiteNa2Cu(SO4)2Mon. 2 : P21
7.AC.50MajzlaniteK2Na(ZnNa)Ca(SO4)4Mon. 2/m : B2/b
7.AC.60Philoxenite(K,Na,Pb)4(Na,Ca)2(Mg,Cu)3(Fe3+0.5Al0.5)(SO4)8Tric. 1 : P1
7.AC.75PetroviteNa12Cu2(SO4)8Mon. 2/m : P21/b

RadioactivityHide

Radioactivity:
Element % Content Activity (Bq/kg) Radiation Type
Uranium (U) 0.0000% 0 α, β, γ
Thorium (Th) 0.0000% 0 α, β, γ
Potassium (K) 13.0244% 4,038 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

Other InformationHide

Health Risks:
No information on health risks for this material has been entered into the database. You should always treat mineral specimens with care.

Internet Links for NatroaphthitaliteHide

References for NatroaphthitaliteHide

Localities for NatroaphthitaliteHide

Showing 1 localities.

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.
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Locality ListHide

- This locality has map coordinates listed. - This locality has estimated coordinates. ⓘ - Click for references and further information on this occurrence. ? - Indicates mineral may be doubtful at this locality. - Good crystals or important locality for species. - World class for species or very significant. (TL) - Type Locality for a valid mineral species. (FRL) - First Recorded Locality for everything else (eg varieties). Struck out - Mineral was erroneously reported from this locality. Faded * - Never found at this locality but inferred to have existed at some point in the past (e.g. from pseudomorphs).

All localities listed without proper references should be considered as questionable.
Russia (TL)
 
  • Kamchatka Krai
    • Milkovsky District
      • Tolbachik Volcanic field
        • Great Fissure eruption (Main Fracture)
          • Northern Breakthrough (North Breach)
            • Second scoria cone
Hålenius et al. (2018) +1 other reference
 
and/or  
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