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Thomsonite-Ca

Formula:
NaCa
 
2
[Al
 
5
Si
 
5
O
 
20
] · 6H
 
2
O
System:OrthorhombicColour:Colourless, white, light ...
Hardness:5 - 5½
Name:For Scottish chemist Thomas Thomson (1773-1852).


Zeolite Group. Natrolite Subgroup.

Classification of Thomsonite-Ca

IMA status:Valid - first described prior to 1959 (pre-IMA) - "Grandfathered"
Strunz 8th edition ID:8/J.21-70
Nickel-Strunz 10th (pending) edition ID:9.GA.10

9 : SILICATES (Germanates)
G : Tektosilicates with zeolitic H2O; zeolite family
A : Zeolites with T5O10 Units – The Fibrous Zeolites
Hey's CIM Ref.:16.10.4

16 : Silicates Containing Aluminum and other Metals
10 : Aluminosilicates of Ca and alkalis
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Type Occurrence of Thomsonite-Ca

Type Locality:Old Kilpatrick, Strathclyde (Dunbartonshire), Scotland, UK
Year of Discovery:1820

Occurrences of Thomsonite-Ca

Geological Setting:In vugs in basalts, as cement in some sandstones.

Physical Properties of Thomsonite-Ca

Lustre:Vitreous, Pearly
Diaphaneity (Transparency):Transparent, Translucent
Colour:Colourless, white, light yellow, light green, pink, brown
Streak:White
Hardness (Mohs):5 - 5½
Tenacity:Brittle
Cleavage:Perfect
Perfect on {010}
Good on {100}
Fracture:Irregular/Uneven, Sub-Conchoidal
Density (measured):2.23 - 2.29 g/cm3
Density (calculated):2.366 g/cm3

Crystallography of Thomsonite-Ca

Crystal System:Orthorhombic
Class (H-M):mmm (2/m 2/m 2/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 Volume:V 2,259.84 ų (Calculated from Unit Cell)
Z:4
Morphology:Crystals commonly prismatic, acicular, bladed, massive
Twinning:On {110}
X-Ray Powder Diffraction:
Image Loading

Radiation - Copper Kα
Data Set:
Horizontal Axis: ° to ° Vertical Axis: % Source Data: Filtered Data: Peaks:
Data courtesy of RRUFF project at University of Arizona, used with permission.

Optical Data of Thomsonite-Ca

Type:Biaxial (+)
RI values: nα = 1.511 - 1.530 nβ = 1.513 - 1.532 nγ = 1.516 - 1.545
2V:Measured: 44° to 75°, Calculated: 44° to 80°
Maximum Birefringence:δ = 0.005 - 0.015

Chart shows birefringence interference colour range (at 30µm thickness) and does not take into account mineral colouration.
Surface Relief:Low
Dispersion:r > v strong

Chemical Properties of Thomsonite-Ca

Formula:
NaCa
 
2
[Al
 
5
Si
 
5
O
 
20
] · 6H
 
2
O
Essential elements:Al, Ca, H, Na, O, Si
All elements listed in formula:Al, Ca, H, Na, O, Si
Common Impurities:K

Relationship of Thomsonite-Ca to other Species

Related Minerals - Nickel-Strunz Grouping):
9.GA.05Gonnardite
Na
 
2
Ca[Al
 
2
Si
 
3
O
 
10
]
 
2
· 7H
 
2
O
9.GA.05Mesolite
Na
 
2
Ca
 
2
[Al
 
2
Si
 
3
O
 
10
]
 
3
· 8H
 
2
O
9.GA.05Natrolite
Na
 
2
[Al
 
2
Si
 
3
O
 
10
] · 2H
 
2
O
9.GA.05Paranatrolite
Na
 
2
Al
 
2
Si
 
3
O
 
10
·3H
 
2
O
9.GA.05Scolecite
Ca[Al
 
2
Si
 
3
O
 
10
] · 3H
 
2
O
9.GA.10Thomsonite-Sr
(Sr,Ca)
 
2
Na[Al
 
5
Si
 
5
O
 
20
]·7H
 
2
O
9.GA.15Edingtonite
Ba[Al
 
2
Si
 
3
O
 
10
] · 4H
 
2
O
9.GA.15Kalborsite
K
 
6
[Cl|B(OH)
 
4
|Al
 
4
Si
 
6
O
 
20
]
Related Minerals - Hey's Index Grouping:
16.10.1Bytownite
(Ca,Na)[Al(Al,Si)Si
 
2
O
 
8
]
16.10.2Lisetite
CaNa
 
2
Al
 
4
Si
 
4
O
 
16
16.10.5Gonnardite
Na
 
2
Ca[Al
 
2
Si
 
3
O
 
10
]
 
2
· 7H
 
2
O
16.10.6Mesolite
Na
 
2
Ca
 
2
[Al
 
2
Si
 
3
O
 
10
]
 
3
· 8H
 
2
O
16.10.7Faujasite
16.10.8Garronite
Na
 
2
Ca
 
5
Al
 
12
Si
 
20
O
 
64
·27H
 
2
O
16.10.9Boggsite
Ca
 
8
Na
 
3
(Si,Al)
 
96
O
 
192
·70H
 
2
O
16.10.10Herschelite
16.10.11Phillipsite
16.10.12Fedorite
KNa
 
4
Ca
 
4
[HSi
 
4
O
 
10
]
 
4
· 6H
 
2
O
16.10.13Willhendersonite
KCa[Al
 
3
Si
 
3
O
 
12
] · 5H
 
2
O
16.10.14Barrerite
(Na,K,Ca
 
0.5
)
 
2
[Al
 
2
Si
 
7
O
 
18
] · 7H
 
2
O
16.10.15Mordenite
(Na
 
2
,Ca,K
 
2
)Al
 
2
Si
 
10
O
 
24
·7H
 
2
O
16.10.16Reyerite
(Na,K)
 
2
Ca
 
14
(Si,Al)
 
24
O
 
58
(OH)
 
8
·6H
 
2
O
16.10.17Lévyne
16.10.18Clinoptilolite
16.10.19Heulandite
16.10.20Gobbinsite
Na
 
4
(Ca,Mg,K
 
2
)Al
 
6
Si
 
10
O
 
32
·12H
 
2
O
16.10.21Stilbite
16.10.22Dachiardite
(Na,K,Ca
 
0
·5)
 
4
(Al
 
4
Si
 
20
)O
 
48
·18H
 
2
O
16.10.23Offretite
KCaMgAl
 
5
Si
 
13
O
 
36
·16H
 
2
O or near
16.10.24Perlialite
K
 
9
Na(Ca,Sr)[Al
 
2
Si
 
4
O
 
12
]
 
6
· 15H
 
2
O
16.10.25Erionite
16.10.26Paulingite
16.10.27Sodium Dachiardite
(Na
 
2
,Ca,K
 
2
)
 
4-5
Al
 
8
Si
 
40
O
 
96
·26H
 
2
O
16.10.28Mazzite-Mg
K
 
2
Mg
 
2
Ca
 
1.5
Al
 
9.5
Si
 
26.5
O
 
72
·28H
 
2
O or near
16.10.29Roggianite
Ca
 
2
Be(OH)
 
2
Al
 
2
Si
 
4
O
 
13
·2.5H
 
2
O

Other Names for Thomsonite-Ca

Synonyms:
BagotiteCarphostilbiteCharphostilbiteComptoniteEchellite
FaröeliteFarölithKarphostilbiteKoodiliteLintonite
MesolitineMézolineOzarkitePicrothomsoniteThompsonite
TonsoniteTriploclaseTriploklasTripoclase
German names:
BagotitCarphostilbitCharphostilbitComptonitEchellit
FaröelitKarphostilbitKoodilitLintonitOzarkit
PicrothomsonitThompsonitThomsonitTonsonit
Russian names:
Томсонит-Ca
Spanish names:
BagotitaCarphostilbitaCharphostilbitaComptonitaEchellita
FaröelitaKarphostilbitaKoodilitaLintonitaOzarkita
PicrothomsonitaThompsonitaThomsonitaTonsonita
Varieties:
Strontian Thomsonite

Other Information

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

References for Thomsonite-Ca

Reference List:American Mineralogist (1992): 77: 685.

Acta Crystallographica: C46: 1370-1373.

Lee, Y., J.A. Hriljac, A. Studer & T. Vogt (2004b), Anisotropic compression of edingtonite and thomsonite to 6 GPa at room temperature: Physics and Chemistry of Minerals: 31: 22-27.

Internet Links for Thomsonite-Ca

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    Localities for Thomsonite-Ca

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