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Truscottite
A valid IMA mineral species - grandfathered
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About Truscottite
Formula:
(Ca,Mn)14Si24O58(OH)8 · 2H2O
Colour:
Colourless, white
Lustre:
Pearly
Hardness:
3½
Specific Gravity:
2.47 - 2.48
Crystal System:
Trigonal
Member of:
Name:
Named after Samuel John Truscott (6 August 1870, Fowey, Cornwall, England - 26 September 1950, Hampstead, London, England), professor of mining, Royal School of Mines, London, England.
This page provides mineralogical data about Truscottite.
Unique Identifiers
Mindat ID:
4033
Long-form identifier:
mindat:1:1:4033:0
IMA Classification of Truscottite
Approved, 'Grandfathered' (first described prior to 1959)
IMA Formula:
Ca14Si24O58(OH)8·2H2O
First published:
1914
Classification of Truscottite
9.EE.35
9 : SILICATES (Germanates)
E : Phyllosilicates
E : Single tetrahedral nets of 6-membered rings connected by octahedral nets or octahedral bands
9 : SILICATES (Germanates)
E : Phyllosilicates
E : Single tetrahedral nets of 6-membered rings connected by octahedral nets or octahedral bands
73.2.2a.2
73 : PHYLLOSILICATES Condensed Tetrahedral Sheets
2 : Condensed Tetrahedral Sheets with double and single layers
73 : PHYLLOSILICATES Condensed Tetrahedral Sheets
2 : Condensed Tetrahedral Sheets with double and single layers
14.18.15
14 : Silicates not Containing Aluminum
18 : Silicates of Mn and Na, K, Mg, Ca or Fe
14 : Silicates not Containing Aluminum
18 : Silicates of Mn and Na, K, Mg, Ca or Fe
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 |
|---|---|---|
| Tst | IMA–CNMNC | Warr, L.N. (2021). IMA–CNMNC approved mineral symbols. Mineralogical Magazine, 85(3), 291-320. doi:10.1180/mgm.2021.43 |
| Tst | Warr (2020) | Warr, L.N. (2020) Recommended abbreviations for the names of clay minerals and associated phases. Clay Minerals, 55, 261–264 doi:10.1180/clm.2020.30 |
Pronunciation of Truscottite
Pronunciation:
| Play | Recorded by | Country |
|---|---|---|
| Jolyon Ralph | United Kingdom |
Physical Properties of Truscottite
Pearly
Transparency:
Transparent, Translucent
Comment:
on cleavage
Colour:
Colourless, white
Streak:
White
Hardness:
3½ on Mohs scale
Cleavage:
Perfect
on {0001}
on {0001}
Fracture:
Micaceous
Density:
2.47 - 2.48 g/cm3 (Measured) 2.47 g/cm3 (Calculated)
Optical Data of Truscottite
Type:
Uniaxial (-)
RI values:
nω = 1.549 - 1.552 nε = 1.522 - 1.530
Max. Birefringence:
δ = 0.022 - 0.027
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:
None to Very Low
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 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.
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 Truscottite
Mindat Formula:
(Ca,Mn)14Si24O58(OH)8 · 2H2O
Element Weights:
Common Impurities:
Ti,Al,Fe,Mg,Na,K,C,S
Crystallography of Truscottite
Crystal System:
Trigonal
Cell Parameters:
a = 9.73 Å, c = 18.83 Å
Ratio:
a:c = 1 : 1.935
Unit Cell V:
1,543.86 ų (Calculated from Unit Cell)
Z:
1
Morphology:
Scales, spheroidal aggregates of fibrous platy crystals
Comment:
Point Group: 3 or 3; Space Group: P3 or P3
X-Ray Powder Diffraction
Powder Diffraction Data:
| d-spacing | Intensity |
|---|---|
| 3.141 Å | (100) |
| 2.840 Å | (80) |
| 4.21 Å | (70) |
| 1.839 Å | (70) |
| 18.8 Å | (60) |
| 2.638 Å | (55) |
| 3.501 Å | (45) |
Comments:
resembles gyrolite or reyerite.
Geological Environment
Paragenetic Mode(s):
| Paragenetic Mode | Earliest Age (Ga) |
|---|---|
| Near-surface Processes | |
| 23 : Subaerial aqueous alteration by non-redox-sensitive fluids (see also #47) |
Type Occurrence of Truscottite
Place of Conservation of Type Material:
Natural History Museum, London 1925,1044
Geological Setting of Type Material:
Epithermal gold, silver quartz veins in altered pyroclastics.
Other Language Names for Truscottite
Relationship of Truscottite to other Species
Member of:
Other Members of Reyerite Group:
| Kodamaite | Na3(Ca5Na)Si16O36(OH)4F2 · (14-x)H2O | Tric. 1 : P1 |
| Minehillite | (K,Na)2-3Ca28Zn4Al4Si40O112(OH)16 | Hex. |
| Reyerite | (Na,K)2Ca14(Si,Al)24O58(OH)8 · 6H2O | Trig. 3 : P3 |
Common Associates
Associations Based on Photo Data:
| 4 photos of Truscottite associated with Analcime | Na(AlSi2O6) · H2O |
| 4 photos of Truscottite associated with Natrolite | Na2Al2Si3O10 · 2H2O |
| 3 photos of Truscottite associated with Thomsonite Subgroup | |
| 3 photos of Truscottite associated with Calcite | CaCO3 |
| 3 photos of Truscottite associated with Saponite | Ca0.25(Mg,Fe)3((Si,Al)4O10)(OH)2 · nH2O |
| 2 photos of Truscottite associated with Apophyllite Group | AB4[Si8O20]X · 8H2O |
| 1 photo of Truscottite associated with Thomsonite-Ca | NaCa2[Al5Si5O20] · 6H2O |
| 1 photo of Truscottite associated with Mesolite | Na2Ca2Si9Al6O30 · 8H2O |
Related Minerals - Strunz-mindat Grouping
| 9.EE. | Cairncrossite | Sr2Ca7-xNa2x(Si4O10)4(OH)2(H2O)15-x |
| 9.EE.05 | Bementite | Mn7Si6O15(OH)8 |
| 9.EE.07 | Innsbruckite | Mn33(Si2O5)14(OH)38 |
| 9.EE.10 | 'Brokenhillite' | Mn8Si6O15(OH)10 |
| 9.EE.10 | Mcgillite | (Mn,Fe)8Si6O15(OH)8Cl2 |
| 9.EE.10 | Friedelite | Mn2+8Si6O15(OH,Cl)10 |
| 9.EE.10 | Pyrosmalite-(Mn) | Mn2+8Si6O15(OH,Cl)10 |
| 9.EE.10 | Pyrosmalite-(Fe) | Fe2+8Si6O15(OH,Cl)10 |
| 9.EE.15 | Nelenite | Mn2+16As3+3Si12O36(OH)17 |
| 9.EE.15 | Schallerite | Mn2+16As3Si12O36(OH)17 |
| 9.EE.20 | Palygorskite | ◻Al2Mg2◻2Si8O20(OH)2(H2O)4 · 4H2O |
| 9.EE.20 | Yofortierite | Mn2+Mn2+2Mn2+2◻2Si8O20(OH)2(H2O)4 · 4H2O |
| 9.EE.20 | Windhoekite | Fe3+(Fe3+1.67◻0.33)Ca2◻2Si8O20(OH)2(H2O)4(OH)2 · 6H2O |
| 9.EE.20 | Windmountainite | ◻Fe3+2Mg2◻2Si8O20(OH)2(H2O)4 · 4H2O |
| 9.EE.20 | Ikorskyite | KMn3+(Si4O10) · 3H2O |
| 9.EE.20 | Tuperssuatsiaite | Fe3+Fe3+2(Na◻)◻2Si8O20(OH)2(H2O)4 · 2H2O |
| 9.EE.20 | 'Unnamed (Na-Ca-Fe-Silicate-Hydrate)' | NaCa(Fe2+,Al,Mn)5[Si8O19(OH)](OH)7 · 5H2O |
| 9.EE.25 | Sepiolite | Mg4(Si6O15)(OH)2 · 6H2O |
| 9.EE.25 | Loughlinite | Na2Mg3Si6O16 · 8H2O |
| 9.EE.25 | Falcondoite | (Ni,Mg)4Si6O15(OH)2 · 6H2O |
| 9.EE.25 | Kalifersite | (K,Na)5Fe3+7Si20O50(OH)6 · 12H2O |
| 9.EE.30 | Orlymanite | Ca4Mn3Si8O20(OH)6 · 2H2O |
| 9.EE.30 | Tungusite | Ca4Fe2Si6O15(OH)6 |
| 9.EE.30 | Gyrolite | NaCa16Si23AlO60(OH)8 · 14H2O |
| 9.EE.35 | Reyerite | (Na,K)2Ca14(Si,Al)24O58(OH)8 · 6H2O |
| 9.EE.35 | Kodamaite | Na3(Ca5Na)Si16O36(OH)4F2 · (14-x)H2O |
| 9.EE.40 | Natrosilite | Na2Si2O5 |
| 9.EE.45 | Makatite | Na2Si4O8(OH)2 · 4H2O |
| 9.EE.50 | Varennesite | Na8Mn2Si10O25(OH,Cl)2 · 12H2O |
| 9.EE.55 | Raite | Mn2+Mn2+2Na2(◻1.75Ti0.25)Si8O20(OH)2(H2O)4 · Na(H2O)6 |
| 9.EE.60 | Intersilite | Na6Mn2+Ti[Si10O24(OH)](OH)3 · 4H2O |
| 9.EE.65 | Zakharovite | Na4Mn5Si10O24(OH)6 · 6H2O |
| 9.EE.65 | Shafranovskite | Na3K2(Mn,Fe,Na)4[Si9(O,OH)27](OH)2 · nH2O |
| 9.EE.70 | Zeophyllite | Ca13Si10O28(OH)2F8 · 6H2O |
| 9.EE.75 | Minehillite | (K,Na)2-3Ca28Zn4Al4Si40O112(OH)16 |
| 9.EE.80 | Fedorite | (Na,K)2-3(Ca4Na3)Si16O38(OH,F)2 · 3.5H2O |
| 9.EE.80 | Martinite | (Na,◻,Ca)12Ca4(Si,S,B)14B2O38(OH,Cl)2F2 · 4H2O |
| 9.EE.80 | Ellingsenite | Na5Ca6Si18O38(OH)13 · 6H2O |
| 9.EE.85 | Lalondeite | (Na,Ca)6(Ca,Na)3Si16O38(F,OH)2 · 3H2O |
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 Truscottite
mindat.org URL:
https://www.mindat.org/min-4033.html
Please feel free to link to this page.
Please feel free to link to this page.
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References for Truscottite
Reference List:
Mackay, A. L., Taylor, H. F. W. (1954) Truscottite. Mineralogical Magazine and Journal of the Mineralogical Society, 30 (226) 450-457 doi:10.1180/minmag.1954.030.226.04
MINATO, Hideo, KATO, Akira (1967) Truscottite from the Toi Mine, Shizuoka Prefecture. Mineralogical Journal, 5 (2). 144-156 doi:10.2465/minerj1953.5.144
Gard, J. A., Mitsuda, T., Taylor, H. F. W. (1975) Some observations on Assarsson's Z-phase and its structural relations to gyrolite, truscottite, and reyerite. Mineralogical Magazine, 40 (312) 325-333 doi:10.1180/minmag.1975.040.312.01
Lachowski, E. E., Murray, L. W., Taylor, H. F. W. (1979) Truscottite: composition and ionic substitutions. Mineralogical Magazine, 43 (327) 333-336 doi:10.1180/minmag.1979.043.327.03
Localities for Truscottite
Showing 20 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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Bras de Cilaos, Cilaos, Réunion, France