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Thornasite

A valid IMA mineral species
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04232030017271927038487.jpg
Thornasite

Demix-Varennes quarry, Saint-Amable sill, Varennes & St-Amable, Lajemmerais RCM, Montérégie, Québec, Canada
08539260017271927057008.jpg
Thornasite, etc.

Aris Quarries, Aris, Windhoek Rural, Khomas Region, Namibia
01758960017271927135197.jpg
Thornasite

Aris Quarries, Aris, Windhoek Rural, Khomas Region, Namibia
04232030017271927038487.jpg
Thornasite

Demix-Varennes quarry, Saint-Amable sill, Varennes & St-Amable, Lajemmerais RCM, Montérégie, Québec, Canada
08539260017271927057008.jpg
Thornasite, etc.

Aris Quarries, Aris, Windhoek Rural, Khomas Region, Namibia
01758960017271927135197.jpg
Thornasite

Aris Quarries, Aris, Windhoek Rural, Khomas Region, Namibia
03343220017271927173672.jpg
Thornasite

Demix-Varennes quarry, Saint-Amable sill, Varennes & St-Amable, Lajemmerais RCM, Montérégie, Québec, Canada
08539260017271927057008.jpg
Thornasite, etc.

Aris Quarries, Aris, Windhoek Rural, Khomas Region, Namibia
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About ThornasiteHide

Formula:
(Na,K)12Th3[Si8O19]4 · 18H2O
Colour:
Light green to beige
Lustre:
Vitreous, Waxy, Greasy, Pearly
Specific Gravity:
2.62
Crystal System:
Trigonal
Member of:
Zeolite Group
Name:
The name reflects its composition: thorium (Thor), sodium (Na) and silicon (Si).
This page provides mineralogical data about Thornasite.


Unique IdentifiersHide

Mindat ID:
3947
Long-form identifier:
mindat:1:1:3947:1

IMA Classification of ThornasiteHide

IMA status:
Approved
IMA Formula:
Na12Th3(Si8O19)4 · 18H2O
Approval year:
1985
First published:
1987

Classification of ThornasiteHide

Strunz-mindat (2025):
9.GF.50

9 : SILICATES (Germanates)
G : Tektosilicates with zeolitic H2O; zeolite family
F : Other Rare Zeolites
Dana 8th ed.:
72.1.2.1

72 : PHYLLOSILICATES Two-Dimensional Infinite Sheets with Other Than Six-Membered Rings
1 : Two-Dimensional Infinite Sheets with Other Than Six-Membered Rings with 4-membered rings
Hey's CIM Ref.:
14.11.4

14 : Silicates not Containing Aluminum
11 : Silicates of Th and Hg

Mineral SymbolsHide

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

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

Physical Properties of ThornasiteHide

Lustre:
Vitreous, Waxy, Greasy, Pearly
Transparency:
Transparent, Translucent, Opaque
Colour:
Light green to beige
Streak:
White
Hardness Data:
Could not be measured
Comment:
Could not be measured due to the small crystal size and brittleness.
Tenacity:
Brittle
Fracture:
Irregular/Uneven, Sub-Conchoidal
Density:
2.62(2) g/cm3 (Measured)    2.627 g/cm3 (Calculated)

Optical Data of ThornasiteHide

Type:
Uniaxial (+)
RI values:
nω = 1.510(1) nε = 1.512(1)
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.

Surface Relief:
Moderate

Chemistry of ThornasiteHide

Mindat Formula:
(Na,K)12Th3[Si8O19]4 · 18H2O
Element Weights:
Element% weight
O44.092 %
Si26.349 %
Th20.408 %
Na8.088 %
H1.064 %

Calculated from ideal end-member formula.
Elements listed:
H, K, Na, O, Si, Th - search for minerals with similar chemistry
Common Impurities:
U,Al,Ca,Cl

Crystallography of ThornasiteHide

Crystal System:
Trigonal
Class (H-M):
3m - Ditrigonal Pyramidal
Space Group:
R3m
Setting:
R3m
Cell Parameters:
a = 29.08 Å, c = 17.30 Å
Ratio:
a:c = 1 : 0.595
Unit Cell V:
12,669.68 ų (Calculated from Unit Cell)

Crystal StructureHide

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IDSpeciesReferenceLinkYearLocalityPressure (GPa)Temp (K)
0002591ThornasiteLi Y, Krivovichev S V, Burns P C (2000) The crystal structure of thornasite: A novel interrupted silicate framework American Mineralogist 85 1521-152520000293
CIF Raw Data - click here to close

X-Ray Powder DiffractionHide

Powder Diffraction Data:
d-spacingIntensity
14.54 Å(20)
8.17 Å(30)
7.27 Å(100)
5.09 Å(20)
4.17 Å(70)
3.239 Å(30)
2.890 Å(25)

Geological EnvironmentHide

Paragenetic Mode(s):
Paragenetic ModeEarliest Age (Ga)
Stage 4b: Highly evolved igneous rocks>3.0
35 : Ultra-alkali and agpaitic igneous rocks

Type Occurrence of ThornasiteHide

Type Locality:
ⓘ Poudrette quarry (De-Mix quarry; Demix quarry; Uni-Mix quarry; Carrière Mont Saint-Hilaire; MSH), Mont Saint-Hilaire, La Vallée-du-Richelieu RCM, Montérégie, Québec, Canada
General Appearance of Type Material:
Anhedral crystals to 0.7 mm, embedded in patches of brockite.
Place of Conservation of Type Material:
Canadian Museum of Nature, Ottawa, Ontario, Canada, number 50770 (holotype).
Royal Ontario Museum, Toronto, Ontario, Canada, number M42070 (cotype).
Associated Minerals at Type Locality:
AnalcimeBrockiteYofortierite

Synonyms of ThornasiteHide

Other Language Names for ThornasiteHide

Relationship of Thornasite to other SpeciesHide

Member of:
Zeolite Group
Other Members of Zeolite Group:
AlflarseniteNaCa2Be3Si4O13(OH) · 2H2OMon. 2 : P21
AmiciteK2Na2Al4Si4O16 · 5H2OMon. 2
Ammonioleucite(NH4)(AlSi2O6)Tet. 4/m : I41/a
AnalcimeNa(AlSi2O6) · H2OTric. 1 : P1
ArzamastseviteK6Al5Si6O20(OH)4ClTet. 4 2m : I4 2m
Bellbergite(K,Ba,Sr)2Sr2Ca2(Ca,Na)4[Al3Si3O12]6 · 30H2OHex.
BikitaiteLiAlSi2O6 · H2OTric. 1 : P1
BoggsiteCa8Na3(Si,Al)96O192 · 70H2OOrth. mmm (2/m 2/m 2/m) : Imma
Brewsterite SubgroupZeolite Group.
Chabazite-Levyne SubgroupM[Al2Si4O12] · 6H2O
ChiavenniteCaMnBe2Si5O13(OH)2 · 2H2OMon. 2/m : P21/b
Clinoptilolite Subgroup(Na/Ca/K)3-6[Al6-7Si29-30O72] · 20H2O
CowlesiteCaAl2Si3O10 · 6H2OOrth. mmm (2/m 2/m 2/m)
Dachiardite SubgroupZeolite Group.
DirenzoiteNaK6MgCa2(Al13Si47O120) · 36H2OOrth. mmm (2/m 2/m 2/m) : Pmmn
EdingtoniteBa[Al2Si3O10] · 4H2OOrth. 2 2 2 : P21 21 21
EpistilbiteCaAl2Si6O16 · 5H2OMon.
Erionite SubgroupM2[Al4Si14O36] · 15H2O
FabrièsiteNa3Al3Si3O12 · 2H2OOrth. mm2 : Pmm2
Faujasite SubgroupM3.5[Al7Si17O48] · 32H2O
Ferrierite SubgroupName used for unanalysed specimens that could be either ferrierite-K, ferrierite-Mg, ...
FerrochiavenniteCa1-2Fe[(Si,Al,Be)5Be2O13(OH)2] · 2H2OMon. 2/m : P21/b
Flörkeite(K3Ca2Na)[Al8Si8O32] · 12H2OTric. 1 : P1
Garronite Subgroup
GaultiteNa4Zn2Si7O18 · 5H2OOrth. mm2 : Fdd2
Gismondine SubgroupZeolite Group.
Gmelinite SubgroupIn 1997, gmelinite was split into Gmelinite-Ca, Gmelinite-Na and Gmelinite-K.
GobbinsiteNa5(Si11Al5)O32 · 11H2OOrth. mmm (2/m 2/m 2/m) : Pnma
GoosecreekiteCa[Al2Si6O16] · 5H2OMon. 2 : P21
GottardiiteNa3Mg3Ca5Al19Si117O272 · 93H2OOrth. mmm (2/m 2/m 2/m) : Cmca
Heulandite Subgroup(Na/Ca/K)5-6[Al8-9 Si27-28 O72] · nH2O
HsianghualiteCa3Li2(Be3Si3O12)F2Iso. 4 3 2 : I41 3 2
KalborsiteK6Al4BSi6O20(OH)4ClTet. 4 2m : P4 21c
KirchhoffiteCs(BSi2O6)Tet. 4/mmm (4/m 2/m 2/m) : I41/acd
LaumontiteCaAl2Si4O12 · 4H2OMon. 2/m : B2/m
LeuciteK(AlSi2O6)Tet. 4/m : I41/a
LimousiniteBaCa[Be4P4O16] · 6H2OMon. 2/m : P21/b
LithositeK6Al4Si8O25 · 2H2OMon.
Loomisite Ba[Be2P2O8] · H2OMon. m
LovdariteK2Na6Be4Si14O36 · 9H2OOrth. mm2
MaricopaitePb7Ca2(Si,Al)48O100 · 32H2OOrth.
MartinandresiteBa2(Al4Si12O32) · 10H2OOrth. mmm (2/m 2/m 2/m) : Pmmn
Mazzite SubgroupZeolite Group.
MeieriteBa44Si66Al30O192Cl25(OH)33Iso. m3m (4/m 3 2/m) : Im3m
MerlinoiteK5Ca2(Si23Al9)O64 · 24H2OOrth. mmm (2/m 2/m 2/m) : Immm
Montesommaite(K,Na)9Al9Si23O64 · 10H2OOrth. mm2 : Fdd2
Mordenite(Na2,Ca,K2)4(Al8Si40)O96 · 28H2OOrth.
MountainiteKNa2Ca2[Si8O19(OH)] · 6H2OMon. 2/m : P2/b
MutinaiteNa3Ca4Si85Al11O192 · 60H2OOrth. mmm (2/m 2/m 2/m) : Pnma
NabesiteNa2BeSi4O10 · 4H2OOrth. 2 2 2 : P21 21 21
Natrolite SubgroupA subgroup of the Zeolite Group.
OffretiteKCaMg(Si13Al5)O36 · 15H2OHex. 6 m2 : P6m2
PahasapaiteLi8(Ca,Li,K)10.5Be24(PO4)24 · 38H2OIso. 2 3 : I2 3
ParthéiteCa2(Si4Al4) O15 (OH)2 · 4H2OMon. 2/m : B2/b
Paulingite SubgroupPaulingite was originally described in 1960.
PerlialiteK9Na(Ca,Sr)[Al2Si4O12]6 · 15H2OHex. 6/mmm (6/m 2/m 2/m) : P6/mmm
Phillipsite Subgroup(Ca0.5,K,Na,Ba0.5)4-7[Al4-7Si12-9O32] . 12H2O
Pollucite(Cs,Na)2(Al2Si4O12) · 2H2OIso. m3m (4/m 3 2/m) : Ia3d
RoggianiteCa2Be(OH)2Al2Si4O13 · 2.5H2OTet. 4/mmm (4/m 2/m 2/m) : I4/mcm
RongibbsitePb2(Si4Al)O11(OH) Mon. 2/m : B2/m
Stilbite SubgroupM6-7[Al8-9Si27-28O72] · nH2O
Terranovaite(Na,Ca)8(Si68Al12)O160 · 29H2OOrth.
Thomsonite SubgroupThe large majority of "thomsonite" is thomsonite-Ca.
Tschernichite(Ca,Na2)[Al2Si4O12] · 4-8H2OTet. 4/mmm (4/m 2/m 2/m) : P4/mmm
TschörtneriteCa4(Ca,Sr,K,Ba)3Cu3[Al3Si3O12]4(OH)8 · nH2OIso. m3m (4/m 3 2/m) : Fm3m
UM1996-38-SiO:AlCaHNaNa-Ca-Al-Si-O-H
UM1999-33-SiO:AlHKNaK7Na5Al12Si20O64 · 24H2O
UM2002-40-SiO:AlCaHKMgNa(Mg,Ca,Na,K)7.5(Al12.8Si51.2)O128 · 65H2OTet. 4 2 2 : P41 2 2
Unnamed (Ca analogue of Merlinoite)(Ca,K,Na)5(Ca,Ba)2Al9Si23O64 · 23H2O ?
WairakiteCa(Al2Si4O12) · 2H2OMon. 2/m : B2/m
WeinebeneiteCaBe3(PO4)2(OH)2 · 4H2OMon. m : Bb
Wenkite(Ba,K)4(Ca,Na)6[(Si,Al)20O39(OH)2](SO4)3 · 0.5H2OHex. 6 m2 : P62m
Wilancookite(Ba5Li2◻)Ba6Be24P24O96 · 26H2OIso. 2 3 : I2 3
WillhendersoniteKCa[Al3Si3O12] · 5H2OTric. 1 : P1
YugawaraliteCaAl2Si6O16 · 4H2OMon. m : Pb

Common AssociatesHide

Associated Minerals Based on Photo Data:
4 photos of Thornasite associated with AegirineNaFe3+Si2O6
4 photos of Thornasite associated with VilliaumiteNaF
3 photos of Thornasite associated with NatroliteNa2Al2Si3O10 · 2H2O
3 photos of Thornasite associated with TuperssuatsiaiteFe3+Fe3+2(Na◻)◻2Si8O20(OH)2(H2O)4 · 2H2O
2 photos of Thornasite associated with EllingseniteNa5Ca6Si18O38(OH)13 · 6H2O

Related Minerals - Strunz-mindat GroupingHide

9.GF.05Terranovaite(Na,Ca)8(Si68Al12)O160 · 29H2OOrth.
9.GF.10GottardiiteNa3Mg3Ca5Al19Si117O272 · 93H2OOrth. mmm (2/m 2/m 2/m) : Cmca
9.GF.15LovdariteK2Na6Be4Si14O36 · 9H2OOrth. mm2
9.GF.20GaultiteNa4Zn2Si7O18 · 5H2OOrth. mm2 : Fdd2
9.GF.25FerrochiavenniteCa1-2Fe[(Si,Al,Be)5Be2O13(OH)2] · 2H2OMon. 2/m : P21/b
9.GF.25ChiavenniteCaMnBe2Si5O13(OH)2 · 2H2OMon. 2/m : P21/b
9.GF.30Tschernichite(Ca,Na2)[Al2Si4O12] · 4-8H2OTet. 4/mmm (4/m 2/m 2/m) : P4/mmm
9.GF.35MutinaiteNa3Ca4Si85Al11O192 · 60H2OOrth. mmm (2/m 2/m 2/m) : Pnma
9.GF.40TschörtneriteCa4(Ca,Sr,K,Ba)3Cu3[Al3Si3O12]4(OH)8 · nH2OIso. m3m (4/m 3 2/m) : Fm3m
9.GF.55DirenzoiteNaK6MgCa2(Al13Si47O120) · 36H2OOrth. mmm (2/m 2/m 2/m) : Pmmn
9.GF.60MeieriteBa44Si66Al30O192Cl25(OH)33Iso. m3m (4/m 3 2/m) : Im3m
9.GF.65RongibbsitePb2(Si4Al)O11(OH) Mon. 2/m : B2/m

RadioactivityHide

Radioactivity:
Element % Content Activity (Bq/kg) Radiation Type
Uranium (U) 0.0000% 0 α, β, γ
Thorium (Th) 20.4082% 816,328 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 ThornasiteHide

In UV light:
Bright apple-green under long- and short-wave ultraviolet light.

Other InformationHide

Thermal Behaviour:
Heating at 300°C results in complete collapse of the structure.
Notes:
Slightly metamict.

Slightly attacked by 1:1 HCl at room temperature. Unaffected by either 1:1 HNO3 or H2SO4.
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 ThornasiteHide

References for ThornasiteHide

Localities for ThornasiteHide

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 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.
Canada (TL)
 
  • Québec
    • Montérégie
      • La Vallée-du-Richelieu RCM
        • Mont Saint-Hilaire
Ansell et al. (1987) +4 other references
      • Lajemmerais RCM
        • Varennes & St-Amable
Horváth et al. (1998)
Horváth et al. (1998)
Namibia
 
  • Khomas Region
    • Windhoek Rural
      • Aris
Paula Piilonen +3 other references
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