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Stokesite
A valid IMA mineral species - grandfathered
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About Stokesite
Sir George Gabriel Stokes
Formula:
CaSn[Si3O9] · 2H2O
Colour:
Colourless, white, light blue
Lustre:
Vitreous, Pearly
Hardness:
6
Specific Gravity:
3.185
Crystal System:
Orthorhombic
Name:
Named after Sir George Gabriel Stokes (13 August 1819, Skreen, County Sligo, Ireland - 1 February 1903, Cambridge, England), mathematician and physicist, University of Cambridge (England), after whom is named Stokes's law, describing the force acting on a particle moving in a fluid medium.
This page provides mineralogical data about Stokesite.
Unique Identifiers
Mindat ID:
3793
Long-form identifier:
mindat:1:1:3793:4
IMA Classification of Stokesite
Approved, 'Grandfathered' (first described prior to 1959)
IMA Formula:
CaSn4+Si3O9·2H2O
First published:
1899
Classification of Stokesite
9.DM.05
9 : SILICATES (Germanates)
D : Inosilicates
M : Inosilicates with 6-periodic single chains
9 : SILICATES (Germanates)
D : Inosilicates
M : Inosilicates with 6-periodic single chains
65.5.1.1
65 : INOSILICATES Single-Width,Unbranched Chains,(W=1)
5 : Single-Width Unbranched Chains, W=1 with chains P=6
65 : INOSILICATES Single-Width,Unbranched Chains,(W=1)
5 : Single-Width Unbranched Chains, W=1 with chains P=6
14.12.3
14 : Silicates not Containing Aluminum
12 : Silicates of Sn
14 : Silicates not Containing Aluminum
12 : Silicates of Sn
Mineral Symbols
As of 2021 there are now IMA–CNMNC approved mineral symbols (abbreviations) for each mineral species, useful for tables and diagrams.
| Symbol | Source | Reference for Standard |
|---|---|---|
| Sks | IMA–CNMNC | Warr, L.N. (2021). IMA–CNMNC approved mineral symbols. Mineralogical Magazine, 85(3), 291-320. doi:10.1180/mgm.2021.43 |
Physical Properties of Stokesite
Vitreous, Pearly
Transparency:
Transparent, Translucent
Comment:
pearly on {100}
Colour:
Colourless, white, light blue
Streak:
White
Hardness:
6 on Mohs scale
Tenacity:
Brittle
Cleavage:
Perfect
Perfect on {101}
imperfect on {100}
Perfect on {101}
imperfect on {100}
Fracture:
Conchoidal
Density:
3.185 g/cm3 (Measured) 3.211 g/cm3 (Calculated)
Optical Data of Stokesite
Type:
Biaxial (+)
RI values:
nα = 1.609 nβ = 1.613 nγ = 1.619
2V:
Measured: 69° , Calculated: 66° to 70°
Max. Birefringence:
δ = 0.010
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:
High (positive)
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 moderate
Chemistry of Stokesite
Mindat Formula:
CaSn[Si3O9] · 2H2O
Element Weights:
Crystallography of Stokesite
Crystal System:
Orthorhombic
Class (H-M):
mmm(2/m2/m2/m) - Dipyramidal
Space Group:
Pnna
Setting:
Pnna
Cell Parameters:
a = 14.465 Å, b = 11.625 Å, c = 5.235 Å
Ratio:
a:b:c = 1.244 : 1 : 0.45
Unit Cell V:
880.29 ų (Calculated from Unit Cell)
Z:
4
Morphology:
Prismatic crystals, spherical and radial fibrous aggregates.
Crystal Structure
Load
Unit Cell | Unit Cell Packed
2x2x2 | 3x3x3 | 4x4x4
Unit Cell | Unit Cell Packed
2x2x2 | 3x3x3 | 4x4x4
Show
Big Balls | Small Balls | Just Balls | Spacefill
Polyhedra Off | Si Polyhedra | All Polyhedra
Remove metal-metal sticks
Big Balls | Small Balls | Just Balls | Spacefill
Polyhedra Off | Si Polyhedra | All Polyhedra
Remove metal-metal sticks
Display Options
Black Background | White Background
Perspective On | Perspective Off
2D | Stereo | Red-Blue | Red-Cyan
Black Background | White Background
Perspective On | Perspective Off
2D | Stereo | Red-Blue | Red-Cyan
View
CIF File Best | x | y | z | a | b | c
CIF File Best | x | y | z | a | b | c
Rotation
Stop | Start
Stop | Start
Labels
Console Off | On | Grey | Yellow
Console Off | On | Grey | Yellow
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) |
|---|---|---|---|---|---|---|---|
| 0014440 | Stokesite | Vorma A (1963) Crystal structure of stokesite, CaSnSi3O9*2H2O Mineralogical Magazine 33 615-617 |  | 1963 | 0 | 293 |
CIF Raw Data - click here to close
X-Ray Powder Diffraction
Powder Diffraction Data:
| d-spacing | Intensity |
|---|---|
| 3.99 Å | (100) |
| 2.89 Å | (100 broad) |
| 7.25 Å | (80) |
| 1.556 Å | (70) |
| 5.82 Å | (60) |
| 4.54 Å | (60) |
| 3.55 Å | (60) |
Comments:
Roscommon Cliff, England.
Geological Environment
Paragenetic Mode(s):
| Paragenetic Mode | Earliest Age (Ga) |
|---|---|
| Stage 4b: Highly evolved igneous rocks | >3.0 |
| 34 : Complex granite pegmatites |
Type Occurrence of Stokesite
Place of Conservation of Type Material:
Cambridge University, England
Geological Setting of Type Material:
On axinite
Associated Minerals at Type Locality:
Other Language Names for Stokesite
Common Associates
Associations Based on Photo Data:
| 74 photos of Stokesite associated with Albite | Na(AlSi3O8) |
| 46 photos of Stokesite associated with Muscovite | KAl2(AlSi3O10)(OH)2 |
| 37 photos of Stokesite associated with Microcline | K(AlSi3O8) |
| 36 photos of Stokesite associated with 'Smoky Quartz' | SiO2 |
| 22 photos of Stokesite associated with 'Stannomicrolite (of Hogarth 1977)' | (Sn2+,Fe2+,Mn2+)2(Ta,Nb,Sn4+)2(O,OH)7 |
| 15 photos of Stokesite associated with Lepidolite | |
| 12 photos of Stokesite associated with Microlite Group | A2-mTa2X6-wZ1-n |
| 11 photos of Stokesite associated with Cookeite | (LiAl4◻)[AlSi3O10](OH)8 |
| 5 photos of Stokesite associated with 'Plumbomicrolite (of Hogarth 1977)' | |
| 5 photos of Stokesite associated with Tourmaline | AD3G6(T6O18)(BO3)3X3Z |
Related Minerals - Strunz-mindat Grouping
| 9.DM. | Kesebolite-(Ce) | CeCa2Mn(AsO4)(SiO3)3 |
| 9.DM.10 | Calciohilairite | CaZr[SiO3]3 · 3H2O |
| 9.DM.10 | Pyatenkoite-(Y) | Na5YTi[SiO3]6 · 6H2O |
| 9.DM.10 | Hilairite | Na2Zr[SiO3]3 · 3H2O |
| 9.DM.10 | Komkovite | BaZr[Si3O9] · 3H2O |
| 9.DM.10 | Sazykinaite-(Y) | Na5YZr[SiO3]6 · 6H2O |
| 9.DM.15 | Plumbogaidonnayite | PbZrSi3O9 · 2H2O |
| 9.DM.15 | Gaidonnayite | Na2Zr(Si3O9) · 2H2O |
| 9.DM.15 | Georgechaoite | NaKZr[Si3O9] · 2H2O |
| 9.DM.20 | Chkalovite | Na2BeSi2O6 |
| 9.DM.25 | Vlasovite | Na2ZrSi4O11 |
| 9.DM.30 | Revdite | Na16Si16O27(OH)26 · 28H2O |
| 9.DM.35 | Scheuchzerite | Na(Mn,Mg,Zn)9[VSi9O28(OH)](OH)3 |
| 9.DM.40 | Terskite | Na4ZrSi6O16 · 2H2O |
| 9.DM.40 | Hydroterskite | Na2ZrSi6O12(OH)6 |
Other Information
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 Stokesite
mindat.org URL:
https://www.mindat.org/min-3793.html
Please feel free to link to this page.
Please feel free to link to this page.
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External Links:
Mineral Dealers:
References for Stokesite
Reference List:
Hutchinson, A. (1900) On Stokesite, a new mineral containing tin, from Cornwall. Mineralogical Magazine and Journal of the Mineralogical Society, 12 (57) 274-281 doi:10.1180/minmag.1900.012.57.07
Gay, P., Rickson, K. O. (1960) X-ray data on stokesite. Mineralogical Magazine and Journal of the Mineralogical Society, 32 (249) 433-435 doi:10.1180/minmag.1960.032.249.02
Čech, F. (1961) Occurrence of stokesite in Czechoslovakia. Mineralogical Magazine and Journal of the Mineralogical Society, 32 (252) 673-675 doi:10.1180/minmag.1961.032.252.01
Vorma, Atso (1963) Crystal structure of stokesite, CaSnSi3O9·2H2O. Mineralogical Magazine and Journal of the Mineralogical Society, 33 (262) 615-617 doi:10.1180/minmag.1963.033.262.10
Černý, P. (1966) A new Czechoslovak occurrence of stokesite. Mineralogical Magazine and Journal of the Mineralogical Society, 35 (274) 835-837 doi:10.1180/minmag.1966.035.274.04
Localities for Stokesite
Showing 40 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.
Australia | |
| Anon (2013) |
Brazil | |
| White (1973) +3 other references |
China | |
| Yuan et al. (2017) |
Czech Republic | |
| Novák et al. (2015) |
| Novák et al. (2013) +1 other reference |
| Veselovskỳ et al. (2018) |
| Houzar |
| Čech (1961) +1 other reference |
| Škoda et al. (2006) +2 other references |
| Výravský et al. (2024) |
| Houzar et al. (2009) +1 other reference |
| Strübel +2 other references |
| Petr Pauliš (2001) | |
Finland | |
| Kristiansen (2023) |
France | |
| Queneau (n.d.) |
Germany | |
| Martin et al. (2023) +1 other reference |
| Meyer et al. (2024) |
| Trinkler (2010) |
| Kern et al. (2017) |
Japan | |
| Miyawaki et al (1987) |
| Nikao (1977) | |
| Ritsuro Miyawaki et al (2004) +1 other reference | |
Morocco | |
| Econ Geol (1989) |
| Sonnet (1981) |
Poland | |
| Mil et al. (2023) +1 other reference |
Portugal | |
| Ramos et al. (2024) |
Russia | |
| Voloshin and Pakhymovsky (1988) |
| |
| Voloshin and Pakhymovsky (1988) +2 other references |
| Ivashchenko (2021) | |
Spain | |
| Sainz de Baranda Graf et al. (2026) |
| Calvo Rebollar et al. (2022) |
| Tánago et al. (2012) +1 other reference |
Sweden | |
| Langhof et al. (1998) |
UK | |
| Couper et al. (1977) +2 other references |
| Hutchinson (1899) +1 other reference |
| Couper et al. (1977) | |
USA | |
| - (1955) |
| www.minsocam.org +2 other references |
Vietnam | |
| Kubernátová et al. (2019) |
Quick NavTopAbout StokesiteUnique IdentifiersIMA Classification Classification Mineral SymbolsPhysical Properties Optical Data Chemistry Crystallography Crystal StructureX-Ray Powder DiffractionGeological EnvironmentType Occurrence Other LanguagesCommon AssociatesStrunz-MindatOther InformationInternet Links References Localities Locality List
Urucum claim, Barra do Cuieté, Conselheiro Pena, Minas Gerais, Brazil