Barrydawsonite-(Y)
A valid IMA mineral species
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Formula:
Na1.5Y0.5CaSi3O8(OH)
Colour:
Colourless
Crystal System:
Monoclinic
Member of:
Name:
Name is for Professor John Barry Dawson (19 June 1932 - 2 February 2013, Edinburgh, Scotland), an eminent British petrologist who made ground-breaking studies of silica undersaturated rocks of the Earth’s crust and mantle. He was particularly well-known for his discovery of the world’s only active carbonatite volcano, Oldoinyo Lengai (Tanzania). Over his career he worked at the Tanganyika Geological Survey, and the universities of St Andrews, Sheffield, and Edinburgh. Prof. Dawson also had a long association with the International Kimberlite Conferences, of which he was a co-founder.
A pyroxenoid closely related to the Pectolite-Sérandite Series. Barrydawsonite-(Y) is related to pectolite by the substitution ½[NaM3+Ca−2] (M3+ = Y,REE), and the only member of the wollastonite group that has the structure of the monoclinic M2abc polytype. Chemically the mineral is somewhat similar to gerenite-(Y), monteregianite-(Y), and yakovenchukite-(Y).
Barrydawsonite-(Y) crystals from the TL commonly have discrete thin rims of Y-bearing pectolite.
The structure contains three metal sites: M(1) is Ca, M(2) is Na0.5(Y,REE)0.5, and M(3) is Na. Coordination number of the sites is the same as in pectolite and serandite, and equals 6 for M(1) and M(2), or 8 for M(3). The M(2)-centred octahedron participates in hydrogen bonding.
Barrydawsonite-(Y) crystals from the TL commonly have discrete thin rims of Y-bearing pectolite.
The structure contains three metal sites: M(1) is Ca, M(2) is Na0.5(Y,REE)0.5, and M(3) is Na. Coordination number of the sites is the same as in pectolite and serandite, and equals 6 for M(1) and M(2), or 8 for M(3). The M(2)-centred octahedron participates in hydrogen bonding.
Unique Identifiers
Mindat ID:
46417
Long-form identifier:
mindat:1:1:46417:0
IMA Classification of Barrydawsonite-(Y)
Approved
IMA Formula:
Na1.5Y0.5CaSi3O9H
Approval year:
2014
First published:
2015
Classification of Barrydawsonite-(Y)
9.DG.
9 : SILICATES (Germanates)
D : Inosilicates
G : Inosilicates with 3-periodic single and multiple chains
9 : SILICATES (Germanates)
D : Inosilicates
G : Inosilicates with 3-periodic single and multiple chains
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 |
|---|---|---|
| Bdw-Y | 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 Barrydawsonite-(Y)
Transparency:
Transparent
Colour:
Colourless
Optical Data of Barrydawsonite-(Y)
Type:
Biaxial (+)
RI values:
nα = 1.612(1) nβ = 1.617(1) nγ = 1.630(1)
2V:
Measured: 63° (1), Calculated: 64°
Max. Birefringence:
δ = 0.018
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:
Moderate dispersion, r < v.
Optical Extinction:
Z = b; X ∧ c = 15º in obtuse angle β.
Pleochroism:
Non-pleochroic
Chemistry of Barrydawsonite-(Y)
Mindat Formula:
Na1.5Y0.5CaSi3O8(OH)
Element Weights:
Common Impurities:
Mn,(Fe,Dy)
Crystallography of Barrydawsonite-(Y)
Crystal System:
Monoclinic
Class (H-M):
2/m - Prismatic
Space Group:
P21/b
Setting:
P21/a
Cell Parameters:
a = 15.5026(2) Å, b = 7.0233(1) Å, c = 6.9769(1) Å
γ = 95.149(1)°
γ = 95.149(1)°
Ratio:
a:b:c = 2.207 : 1 : 0.993
Unit Cell V:
756.58 ų
Z:
4
Morphology:
Brown crystals (<1 vol.%) included in amphibole and/or pyroxene.
X-Ray Powder Diffraction
Powder Diffraction Data:
| d-spacing | Intensity |
|---|---|
| 3.272 Å | (27) |
| 3.094 Å | (30) |
| 2.905 Å | (100) |
| 2.721 Å | (17) |
| 2.421 Å | (16) |
| 2.161 Å | (27) |
| 1.7613 Å | (29) |
| 1.7016 Å | (27) |
Reference:
Comments:
From Type Description.
Geological Environment
Paragenetic Mode(s):
| Paragenetic Mode | Earliest Age (Ga) |
|---|---|
| Stage 5: Initiation of plate tectonics | <3.5-2.5 |
| 40 : Regional metamorphism (greenschist, amphibolite, granulite facies) |
Type Occurrence of Barrydawsonite-(Y)
General Appearance of Type Material:
Forms single grains which can be either subhedral prismatic crystals up to 0.2mm x 0.1mm x 0.1mm, or anhedral crystals up to 0.5mm in maximum dimension.
Place of Conservation of Type Material:
Type material is deposited in the collections of the Natural History Museum, London, UK, catalogue number BM 2014-50. Cotype material is deposited in the collections of the Natural History Museum of Los Angeles County, California, USA, catalogue number 64.
Geological Setting of Type Material:
Metamorphosed eudialyte syenite.
Associated Minerals at Type Locality:
Synonyms of Barrydawsonite-(Y)
Other Language Names for Barrydawsonite-(Y)
Dutch:Barrydawsoniet-(Y)
German:Barrydawsonit-(Y)
Relationship of Barrydawsonite-(Y) to other Species
Member of:
Other Members of Wollastonite Group:
| Bustamite | CaMn2+(Si2O6) | Tric. 1 : P1 |
| Cascandite | CaScSi3O8(OH) | Tric. 1 |
| Dalnegorskite | Ca5Mn2+(Si3O9)2 | Tric. 1 : P1 |
| Ferrobustamite | CaFe2+(Si2O6) | Tric. 1 |
| Mendigite | Mn2Mn2MnCa(Si3O9)2 | Tric. 1 : P1 |
| Murakamiite | LiCa2Si3O8(OH) | Tric. 1 : P1 |
| Pectolite | NaCa2Si3O8(OH) | Tric. 1 : P1 |
| Schizolite | NaCaMnSi3O8(OH) | Tric. 1 : P1 |
| Serandite | NaMn2+2Si3O8(OH) | Tric. 1 : P1 |
| Tanohataite | LiMn2Si3O8(OH) | Tric. 1 : P1 |
| Vistepite | SnMn4B2Si4O16(OH)2 | Tric. 1 : P1 |
| Wollastonite | Ca3(Si3O9) | Tric. 1 : P1 |
Related Minerals - Strunz-mindat Grouping
| 9.DG. | Paratobermorite | Ca5AlSi5O16(OH) · 5H2O |
| 9.DG. | Calcinaksite | KNaCa(Si4O10) · H2O |
| 9.DG. | Alvesite | NaKZrSi6O15 · 2H2O |
| 9.DG.02 | Steedeite | NaMn2[Si3BO9](OH)2 |
| 9.DG.02 | Nolzeite | NaMn2[Si3BO9](OH)2 · 2H2O |
| 9.DG.05 | Murakamiite | LiCa2Si3O8(OH) |
| 9.DG.05 | Serandite | NaMn2+2Si3O8(OH) |
| 9.DG.05 | Bustamite | CaMn2+(Si2O6) |
| 9.DG.05 | Pectolite | NaCa2Si3O8(OH) |
| 9.DG.05 | Tanohataite | LiMn2Si3O8(OH) |
| 9.DG.05 | Dalnegorskite | Ca5Mn2+(Si3O9)2 |
| 9.DG.05 | 'Wollastonite-1A' | CaSiO3 |
| 9.DG.05 | Wollastonite | Ca3(Si3O9) |
| 9.DG.05 | Ferrobustamite | CaFe2+(Si2O6) |
| 9.DG.05 | Schizolite | NaCaMnSi3O8(OH) |
| 9.DG.07 | Cascandite | CaScSi3O8(OH) |
| 9.DG.08 | Plombièrite | Ca5Si6O16(OH)2 · 7H2O |
| 9.DG.10 | Clinotobermorite | Ca5Si6O17 · 5H2O |
| 9.DG.10 | Riversideite | Ca5Si6O16(OH)2 · 2H2O |
| 9.DG.10 | Tobermorite | Ca5Si6O17 · 5H2O |
| 9.DG.12 | Jusite | Na2Ca15Al4Si16O54 · 17H2O |
| 9.DG.12 | Kenotobermorite | Ca4Si6O15(OH)2 · 5H2O |
| 9.DG.15 | Foshagite | Ca4(Si3O9)(OH)2 |
| 9.DG.20 | Jennite | Ca9(Si3O9)2(OH)8 · 8H2O |
| 9.DG.20 | Kamenevite | K2TiSi3O9 · H2O |
| 9.DG.25 | Paraumbite | K3Zr2H(Si3O9)2 · nH2O |
| 9.DG.25 | Umbite | K2(Zr,Ti)Si3O9 · H2O |
| 9.DG.30 | Sørensenite | Na4SnBe2Si6O16(OH)4 |
| 9.DG.32 | Escheite | Ca2NaMnTi5[Si12O34]O2(OH)3 · 12H2O |
| 9.DG.35 | Xonotlite | Ca6(Si6O17)(OH)2 |
| 9.DG.40 | Hillebrandite | Ca2(SiO3)(OH)2 |
| 9.DG.45 | Zorite | Na8(Ti,Nb)5(Si6O17)2(OH,O)5 · 14H2O |
| 9.DG.45 | Chivruaiite | Ca4(Ti,Nb)5(Si6O17)2(OH,O)5 · 13-14H2O |
| 9.DG.50 | Haineaultite | (Na,Ca)5Ca(Ti,Nb)5(Si6O17)2(OH,F)8 · 5H2O |
| 9.DG.55 | Epididymite | Na2Be2Si6O15 · H2O |
| 9.DG.60 | Eudidymite | Na2Be2Si6O15 · H2O |
| 9.DG.65 | Elpidite | Na2ZrSi6O15 · 3H2O |
| 9.DG.65 | Patynite | NaKCa4[Si9O23] |
| 9.DG.67 | Whelanite | Cu2+2Ca6[Si6O17(OH)](CO3)(OH)3 · 2H2O |
| 9.DG.70 | Enricofrancoite | KNaCaSi4O10 |
| 9.DG.70 | Yusupovite | Na2Zr(Si6O15) · 2.5H2O |
| 9.DG.70 | Litidionite | KNaCuSi4O10 |
| 9.DG.70 | Fenaksite | (K,Na)4(Fe,Mn)2(Si4O10)2(OH,F) |
| 9.DG.70 | Manaksite | KNaMnSi4O10 |
| 9.DG.75 | Senkevichite | CsKNaCa2TiO[Si7O18](OH) |
| 9.DG.75 | Tinaksite | K2Na(Ca,Mn2+)2TiO[Si7O18(OH)] |
| 9.DG.75 | Tokkoite | K2Ca4[Si7O18(OH)](OH,F) |
| 9.DG.80 | Fluorcanasite | K3Na3Ca5Si12O30F4 · H2O |
| 9.DG.80 | Canasite | K3Na3Ca5Si12O30(OH)4 |
| 9.DG.85 | Miserite | K1.5-x(Ca,Y,REE)5(Si6O15)(Si2O7)(OH,F)2 · yH2O |
| 9.DG.90 | Frankamenite | K3Na3Ca5(Si12O30)(F,OH)4 · H2O |
| 9.DG.92 | Charoite | (K,Sr)15-16(Ca,Na)32[Si6O11(O,OH)6]2[Si12O18(O,OH)12]2[Si17O25(O,OH)18]2(OH,F)4 · ~3H2O |
| 9.DG.95 | Yuksporite | K4(Ca,Na)14(Sr,Ba)2(◻,Mn,Fe)(Ti,Nb)4(O,OH)4(Si6O17)2(Si2O7)3(H2O,OH)3 |
| 9.DG.97 | Eveslogite | (Na,K,Ca,Sr,Ba)48 [(Ti,Nb,Mn,Fe2+)12Si48O144(OH)12](F,OH,Cl)14 |
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 Barrydawsonite-(Y)
mindat.org URL:
https://www.mindat.org/min-46417.html
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Please feel free to link to this page.
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References for Barrydawsonite-(Y)
Reference List:
Williams, P. A., Hatert, F., Pasero, M., Mills, S. J. (2014) IMA Commission on New Minerals, Nomenclature and Classification (CNMNC), CNMNC Newsletter No. 22. Mineralogical Magazine, 78 (5) 1241-1248 doi:10.1180/minmag.2014.078.5.10
Localities for Barrydawsonite-(Y)
Showing 1 localities.
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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.
Canada (TL) | |
| Williams et al. (2014) +2 other references |
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