Thomsonite-Ca
A valid IMA mineral species - grandfathered
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About Thomsonite-Ca
Thomas Thomson
Formula:
NaCa2[Al5Si5O20] · 6H2O
Colour:
Colourless, white, light yellow, light green, pink, brown
Lustre:
Vitreous, Pearly
Hardness:
5 - 5½
Specific Gravity:
2.23 - 2.29
Crystal System:
Orthorhombic
Member of:
Name:
Renamed in 1820 by Henry James Brooke in honour of Thomas Thomson (12 April 1773, Crieff, Perthshire, Scotland – 2 July 1852, Kilmun, Argyleshire, Scotland), professor of chemistry at the University of Glasgow. Thomson was an indefatigable mineral chemist and contributed enormously to the number of accurate chemical analyses of minerals during his career, as well as having discovered many new mineral species. The suffix -Ca denotes the dominance of calcium in the mineral.
Type Locality:
Zeolite Group.
The calcium analogue of Thomsonite-Sr.
Some habits may be confused with stellerite.
A potential Mg analogue may be present at this locality: https://www.mindat.org/loc-414057.html
The calcium analogue of Thomsonite-Sr.
Some habits may be confused with stellerite.
A potential Mg analogue may be present at this locality: https://www.mindat.org/loc-414057.html
Unique Identifiers
Mindat ID:
3941
Long-form identifier:
mindat:1:1:3941:9
IMA Classification of Thomsonite-Ca
Approved, 'Grandfathered' (first described prior to 1959)
IMA Formula:
NaCa2(Al5Si5)O20·6H2O
Classification of Thomsonite-Ca
9.GA.10
9 : SILICATES (Germanates)
G : Tektosilicates with zeolitic H2O; zeolite family
A : Zeolites with T5O10 Units – The Fibrous Zeolites
9 : SILICATES (Germanates)
G : Tektosilicates with zeolitic H2O; zeolite family
A : Zeolites with T5O10 Units – The Fibrous Zeolites
16.10.4
16 : Silicates Containing Aluminum and other Metals
10 : Aluminosilicates of Ca and alkalis
16 : Silicates Containing Aluminum and other Metals
10 : Aluminosilicates of Ca and alkalis
Mineral Symbols
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.
Please only use the official IMA–CNMNC symbol. Older variants are listed for historical use only.
| Symbol | Source | Reference for Standard |
|---|---|---|
| Thm-Ca | IMA–CNMNC | Warr, L.N. (2021). IMA–CNMNC approved mineral symbols. Mineralogical Magazine, 85(3), 291-320. doi:10.1180/mgm.2021.43 |
| Tmp | Kretz (1983) | Kretz, R. (1983) Symbols of rock-forming minerals. American Mineralogist, 68, 277–279. |
| Thm | Whitney & 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 |
| Tho | The Canadian Mineralogist (2019) | The Canadian Mineralogist (2019) The Canadian Mineralogist list of symbols for rock- and ore-forming minerals (December 30, 2019). download |
Physical Properties of Thomsonite-Ca
Vitreous, Pearly
Transparency:
Transparent, Translucent
Colour:
Colourless, white, light yellow, light green, pink, brown
Streak:
White
Hardness:
5 - 5½ on Mohs scale
Tenacity:
Brittle
Cleavage:
Perfect
Perfect on {010}
Good on {100}
Perfect on {010}
Good on {100}
Fracture:
Irregular/Uneven, Sub-Conchoidal
Density:
2.23 - 2.29 g/cm3 (Measured) 2.366 g/cm3 (Calculated)
Optical Data of Thomsonite-Ca
Type:
Biaxial (+)
RI values:
nα = 1.511 - 1.53 nβ = 1.513 - 1.532 nγ = 1.516 - 1.545
2V:
Measured: 44° to 75°, Calculated: 44° to 80°
Max. Birefringence:
δ = 0.005 - 0.015
Based on recorded range of RI values above.
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.
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:
Low (negative)
Relative to Canada balsam mounting medium (n ≈ 1.537).
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 biaxial acute bisectrix (Bxa) interference figure
- the conoscopic view for a grain cut perpendicular to the acute bisectrix, using
this mineral's 2V. The two small white dots mark the melatopes - the points
where the two optic axes emerge - and are shown only when they fall within the
field of view. The coloured bands are isochromatics, and the dark bands are
isogyres.
Rotate the stage: at 0°/90° the isogyres form a cross through the melatopes; at 45° they pull apart into curved hyperbolas. That splitting on rotation - absent in a uniaxial figure - is the standard diagnostic test for telling biaxial minerals from uniaxial ones. If 2V is large, the melatopes may fall outside the field of view, as they often do at the microscope too.
Rotate the stage: at 0°/90° the isogyres form a cross through the melatopes; at 45° they pull apart into curved hyperbolas. That splitting on rotation - absent in a uniaxial figure - is the standard diagnostic test for telling biaxial minerals from uniaxial ones. If 2V is large, the melatopes may fall outside the field of view, as they often do at the microscope too.
Dispersion:
r > v strong
Chemistry of Thomsonite-Ca
Mindat Formula:
NaCa2[Al5Si5O20] · 6H2O
Element Weights:
Common Impurities:
K
Chemical Analysis
Oxide wt%:
| 1 | |
|---|---|
| SiO2 | 36.45 % |
| Al2O3 | 31.37 % |
| FeO | 0.07 % |
| CaO | 12.60 % |
| MgO | 0.02 % |
| SrO | 1.86 % |
| BaO | 0.03 % |
| Na2O | 3.90 % |
| K2O | 0.05 % |
| H2O | 13.52 % |
| Total: | 99.87 % |
Empirical formulas:
| Sample ID | Empirical Formula |
|---|---|
| 1 | (Ca1.83Sr0.15Fe0.01)AL5.01Si4.94O20·6.11H2O |
Sample references:
Crystallography of Thomsonite-Ca
Crystal System:
Orthorhombic
Class (H-M):
mmm(2/m2/m2/m) - Dipyramidal
Cell Parameters:
a = 13.088(2) Å, b = 13.052(2) Å, c = 13.229(2) Å
Ratio:
a:b:c = 1.003 : 1 : 1.014
Unit Cell V:
2,259.84 ų (Calculated from Unit Cell)
Z:
4
Morphology:
Crystals commonly prismatic, acicular, bladed, massive.
Forms:
Common {100}, {010}, {001}, {110}. Uncommon {101}, {401}, {801}, {0·1·48}. Rare {012}, {111}, {705}, {334}, {502}, {301}, {401}, {021}, {072}, {041}, {071}, {081}, {601}, {0·14·1}, {0·1·50}.
Forms:
Common {100}, {010}, {001}, {110}. Uncommon {101}, {401}, {801}, {0·1·48}. Rare {012}, {111}, {705}, {334}, {502}, {301}, {401}, {021}, {072}, {041}, {071}, {081}, {601}, {0·14·1}, {0·1·50}.
Twinning:
On {110}. This twinning can be cyclic for repetition of 4 crystals.
Reference: Rudy Tschernich on Micro Probe (1996 vol. VIII, n. 4) SEM photo n.489 and one twinned crystal drawing. The sample is from Yellow Lake, Olalla, British Columbia, Canada
Reference: Rudy Tschernich on Micro Probe (1996 vol. VIII, n. 4) SEM photo n.489 and one twinned crystal drawing. The sample is from Yellow Lake, Olalla, British Columbia, Canada
Comment:
Space group Pncn. Note: Thomsonite-Ca with disordered Al/Si-distribution has a = 13.0809(3), b = 13.0597(3), c = 6.6051(1) Å, V = 1128.37(14) Å3 and space group Pbnm (Gatta et al., 2010).
Crystal Structure
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Data courtesy of the American Mineralogist Crystal Structure Database. Click on an AMCSD ID to view structure
| ID | Species | Reference | Link | Year | Locality | Pressure (GPa) | Temp (K) |
|---|---|---|---|---|---|---|---|
| 0005037 | Thomsonite-Ca | Gatta G D, Kahlenberg V, Kaindl R, Rotiroti N, Cappelletti P, de Gennaro M (2010) Crystal structure and low-temperature behavior of "disordered" thomsonite American Mineralogist 95 495-502 |  | 2010 | Terzigno, Somma-Vesuvius volcanic complex, Naples Province, Italy | 0 | 295.5 |
| 0005038 | Thomsonite-Ca | Gatta G D, Kahlenberg V, Kaindl R, Rotiroti N, Cappelletti P, de Gennaro M (2010) Crystal structure and low-temperature behavior of "disordered" thomsonite American Mineralogist 95 495-502 | | 2010 | Terzigno, Somma-Vesuvius volcanic complex, Naples Province, Italy | 0 | 98 |
| 0010164 | Thomsonite-Ca | Stahl K, Kvick A, Smith J V (1990) Thomsonite, a neutron diffraction study at 13 K Acta Crystallographica C46 1370-1373 |  | 1990 | 0 | 293 |
CIF Raw Data - click here to close
X-Ray Powder Diffraction
Loading XRD data...
Data courtesy of RRUFF project at University of Arizona, used with permission.
Powder Diffraction Data:
| d-spacing | Intensity |
|---|---|
| 2.86 Å | (100) |
| 4.64 Å | (90) |
| 2.68 Å | (80) |
| 2.95 Å | (70) |
| 3.51 Å | (65) |
| 6.60 Å | (60) |
| 3.19 Å | (45) |
Comments:
Kadan, Czech Republic. ICDD 19-1344.
Geological Environment
Paragenetic Mode(s):
| Paragenetic Mode | Earliest Age (Ga) |
|---|---|
| Stage 3b: Earth’s earliest hydrosphere | >4.45 |
| 14 : Hot springs, geysers, and other subaerial geothermal minerals | |
| Near-surface Processes | |
| 24 : Authigenic minerals in terrestrial sediments (see also #17) | |
| Stage 5: Initiation of plate tectonics | <3.5-2.5 |
| 38 : Ophiolites | |
| 40 : Regional metamorphism (greenschist, amphibolite, granulite facies) |
Geological Setting:
In vugs in basalts, as cement in some sandstones.
Type Occurrence of Thomsonite-Ca
Geological Setting of Type Material:
Amygdaloids in basalt.
Synonyms of Thomsonite-Ca
Other Language Names for Thomsonite-Ca
Dutch:Thomsoniet-Ca
German:Thomsonit-Ca
Bagotit
Carphostilbit
Charphostilbit
Comptonit
Echellit
Faröelit
Karphostilbit
Koodilit
Lintonit
Ozarkit
Picrothomsonit
Thompsonit
Thomsonit
Tonsonit
Bagotit
Carphostilbit
Charphostilbit
Comptonit
Echellit
Faröelit
Karphostilbit
Koodilit
Lintonit
Ozarkit
Picrothomsonit
Thompsonit
Thomsonit
Tonsonit
Russian:Томсонит-Ca
Simplified Chinese:钙杆沸石
Traditional Chinese:鈣桿沸石
Varieties of Thomsonite-Ca
| Strontium-bearing Thomsonite | A strontian variety. Originally described from Inagli Massif, Aldan, Aldan Shield, Saha Republic (Sakha Republic; Yakutia), Eastern-Siberian Region, Russia. |
Relationship of Thomsonite-Ca to other Species
Member of:
Other Members of Thomsonite Subgroup:
| Thomsonite-Sr | Na(Sr,Ca)2[Al5Si5O20] · 7H2O | Orth. mmm(2/m2/m2/m) |
Common Associates
Associations Based on Photo Data:
| 291 photos of Thomsonite-Ca associated with Mesolite | Na2Ca2Si9Al6O30 · 8H2O |
| 261 photos of Thomsonite-Ca associated with Analcime | Na(AlSi2O6) · H2O |
| 235 photos of Thomsonite-Ca associated with Calcite | CaCO3 |
| 227 photos of Thomsonite-Ca associated with Chabazite | |
| 198 photos of Thomsonite-Ca associated with Natrolite | Na2Al2Si3O10 · 2H2O |
| 138 photos of Thomsonite-Ca associated with Chabazite-Ca | (Ca,K2,Na2)2[Al2Si4O12]2 · 12H2O |
| 118 photos of Thomsonite-Ca associated with Phillipsite Subgroup | (Ca0.5,K,Na,Ba0.5)4-7[Al4-7Si12-9O32] . 12H2O |
| 65 photos of Thomsonite-Ca associated with Apophyllite Group | AB4[Si8O20]X · 8H2O |
| 61 photos of Thomsonite-Ca associated with Stilbite Subgroup | M6-7[Al8-9Si27-28O72] · nH2O |
| 50 photos of Thomsonite-Ca associated with Heulandite Subgroup | (Na/Ca/K)5-6[Al8-9 Si27-28 O72] · nH2O |
Related Minerals - Strunz-mindat Grouping
| 9.GA.05 | Scolecite | CaAl2Si3O10 · 3H2O |
| 9.GA.05 | Paranatrolite | Na2Al2Si3O10 · 3H2O |
| 9.GA.05 | Mesolite | Na2Ca2Si9Al6O30 · 8H2O |
| 9.GA.05 | Natrolite | Na2Al2Si3O10 · 2H2O |
| 9.GA.05 | Gonnardite | (Na,Ca)2(Si,Al)5O10 · 3H2O |
| 9.GA.10 | Thomsonite-Sr | Na(Sr,Ca)2[Al5Si5O20] · 7H2O |
| 9.GA.15 | Edingtonite | Ba[Al2Si3O10] · 4H2O |
| 9.GA.15 | Kalborsite | K6Al4BSi6O20(OH)4Cl |
| 9.GA.15 | Arzamastsevite | K6Al5Si6O20(OH)4Cl |
Other Information
Electrical:
Pyroelectric
Thermal Behaviour:
Before the blowpipe, fuses with intumescence, at 2 to a white enamel.
Notes:
Gelatinizes in HCl.
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 Thomsonite-Ca
mindat.org URL:
https://www.mindat.org/min-3941.html
Please feel free to link to this page.
Please feel free to link to this page.
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References for Thomsonite-Ca
Reference List:
Phillips, Alexander H. (1924) Thomsonite from Peekskill, New York. American Mineralogist, 9 (12) 240-241
Wherry, Edgar T. (1925) Pseudo-isomorphism as illustrated in thomsonite. American Mineralogist, 10 (10) 342-347
Winchell, A. N. (1926) Doubtful mineral species as illustrated by "faroelite". American Mineralogist, 11 (4) 82-89
Hey, Max H. (1932) Studies on the zeolites. Part II. Thomsonite (including faroelite) and gonnardite. Mineralogical Magazine and Journal of the Mineralogical Society, 23 (137) 51-125 doi:10.1180/minmag.1932.023.137.01
Taylor, W. H., Meek, C. A., Jackson, W. W. (1933) The Structures of the Fibrous Zeolites. Zeitschrift für Kristallographie - Crystalline Materials, 84 (1) 373-398 doi:10.1524/zkri.1933.84.1.373
Wise, William, Tschernich, Rudy W. (1978) Habits, crystal forms and composition of thomsonite. The Canadian Mineralogist, 16 (3) 487-493
Alberti, Alberto, Vezzalini, Giovanna, Tazzoli, Vittorio (1981) Thomsonite: a detailed refinement with cross checking by crystal energy calculations. Zeolites, 1 (2) 91-97 doi:10.1016/s0144-2449(81)80021-8
Ståhl, K., Kvick, Å ;., Smith, J. V. (1990) Thomsonite, a neutron diffraction study at 13 K. Acta Crystallographica Section C Crystal Structure Communications, 46 (8) 1370-1373 doi:10.1107/s0108270189013259
Ross, Malcolm, Flohr, Marta J. K., Ross, Daphne R. (1992) Crystalline solution series and order-disorder within the natrolite mineral group. American Mineralogist, 77 (7-8) 685-703
Coombs, Douglas S., Alberti, Alberto, Armbruster, Thomas, Artioli, Gilberto, Colella, Carmine, Galli, Ermanno, Grice, Joel D., Liebau, Friedrich, Mandarino, Joseph A., Minato, Hideo, et al. (1997) Recommended nomenclature for zeolite minerals; report of the Subcommittee on Zeolites of the International Mineralogical Association, Commission on New Minerals and Mineral Names. The Canadian Mineralogist, 35 (6). 1571-1606
Jambor, John L., Roberts, Andrew C. (2001) New mineral names. American Mineralogist, 86 (9) 1112-1115
Pekov, I. V., Lovskaya, E. V., Turchkova, A. G., Chukanov, N. V., Zadov, A. E., Rastsvetaeva, R. K., Kononkova, N. N. (2001) Thomsonite-Sr (Sr,Ca)2Na[Al2Si5O20]·6–7H2O, a new zeolite mineral from Khibiny Massif (Kola Peninsula) and thomsonite-Ca—thomsonite-Sr an isomorphous series. Zapiski Vserossijskogo Mineralogicheskogo Obshchestva, 130 (4) 46-55
Jambor, John L., Grew, Edward S., Roberts, Andrew C. (2002) New mineral names. American Mineralogist, 87. 1509-1513
Mandarino, Joseph A. (2002) New minerals. The Canadian Mineralogist, 40 (5). 1527-1550 doi:10.2113/gscanmin.40.5.1529
Lee, Y., Hriljac, J. A., Studer, A., Vogt, T. (2004) Anisotropic compression of edingtonite and thomsonite to 6 GPa at room temperature. Physics and Chemistry of Minerals, 31 (1) 22-27 doi:10.1007/s00269-003-0330-6
Kol’tsova, T. N. (2005) Zeolites of the natrolite-thomsonite series. Inorganic Materials, 41 (7) 750-756 doi:10.1007/s10789-005-0203-0
Localities for Thomsonite-Ca
Showing 573 localities.
symbol to view information about a locality.
The Locality List
- 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).
All localities listed without proper references should be considered as questionable.
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Pustý Vrch, Folknáře, Děčín, Děčín District, Ústí nad Labem Region, Czech Republic