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Nybøite
A valid IMA mineral species
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Formula:
NaNa2(Mg3Al2)(AlSi7O22)(OH)2
The nybøite group minerals are sodium amphiboles defined with A(Na+K+2Ca)> 0.5 apfu and C(Al+Fe3++2Ti) > 1.5 apfu
Nybøite is defined with
A position: Na dominant
C2+ position: Mg dominant
C3+ position: Al dominant
W position: (OH) dominant
Nybøite is defined with
A position: Na dominant
C2+ position: Mg dominant
C3+ position: Al dominant
W position: (OH) dominant
Colour:
Grey-green; Blue-grey
Lustre:
Vitreous
Hardness:
5 - 6
Specific Gravity:
3.12
Crystal System:
Monoclinic
Member of:
Name:
For the type locality
Name Encoding
ASCII-7:
Nyboite
Unique Identifiers
Mindat ID:
2944
Long-form identifier:
mindat:1:1:2944:1
Similar Names
| Niobite | A synonym of 'Columbite' |
IMA Classification of Nybøite
Approved
IMA Formula:
NaNa2(Mg3Al2)(Si7Al)O22(OH)2
Approval year:
1980
First published:
1981
Approval history:
The root-name nybøite was proposed by D.C. Smith and L. Ungaretti for a new amphibole with the ideal composition NaNa2Mg3Al2(AlSi7)O22(OH)2 and was approved by the IMA in September, 1980. This first publication however did not provide the full mineral data desired by the IMA. A comprehensive description was later published and discussed in Oberti et al. 2003.
Type description reference:
Classification of Nybøite
9.DE.25
9 : SILICATES (Germanates)
D : Inosilicates
E : Inosilicates with 2-periodic double chains, Si4O11; Clinoamphiboles
9 : SILICATES (Germanates)
D : Inosilicates
E : Inosilicates with 2-periodic double chains, Si4O11; Clinoamphiboles
66.1.3c.11
66 : INOSILICATES Double-Width,Unbranched Chains,(W=2)
1 : Amphiboles - Mg-Fe-Mn-Li subgroup
66 : INOSILICATES Double-Width,Unbranched Chains,(W=2)
1 : Amphiboles - Mg-Fe-Mn-Li subgroup
16.8.3
16 : Silicates Containing Aluminum and other Metals
8 : Aluminosilicates of Mg and alkalis
16 : Silicates Containing Aluminum and other Metals
8 : Aluminosilicates of Mg 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 |
|---|---|---|
| Nyb | IMA–CNMNC | Warr, L.N. (2021). IMA–CNMNC approved mineral symbols. Mineralogical Magazine, 85(3), 291-320. doi:10.1180/mgm.2021.43 |
| Nyb | Siivolam & Schmid (2007) | Siivolam, J. and Schmid, R. (2007) Recommendations by the IUGS Subcommission on the Systematics of Metamorphic Rocks: List of mineral abbreviations. Web-version 01.02.07. IUGS Commission on the Systematics in Petrology. download |
| Nyb | 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 |
Physical Properties of Nybøite
Vitreous
Colour:
Grey-green; Blue-grey
Hardness:
5 - 6 on Mohs scale
Density:
3.12 g/cm3 (Measured) 3.13 g/cm3 (Calculated)
Optical Data of Nybøite
Type:
Biaxial (-)
RI values:
nα = 1.65 nγ = 1.67
2V:
Measured: Medium°
Max. Birefringence:
δ = 0.020
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:
Very 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.
No measured or calculated 2V is on file for this mineral, so the value used here (89°) is estimated from its recorded refractive indices and optic sign, not from a direct 2V measurement.
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.
No measured or calculated 2V is on file for this mineral, so the value used here (89°) is estimated from its recorded refractive indices and optic sign, not from a direct 2V measurement.
Pleochroism:
Visible
Comments:
Pale pink-violet; α colourless,β pale brownish-pink,and γ pale bluish-green.
Comments:
The β colour tends towards that characteristic of glaucophane and is quite distinctive.
Chemistry of Nybøite
Mindat Formula:
NaNa2(Mg3Al2)(AlSi7O22)(OH)2
The nybøite group minerals are sodium amphiboles defined with A(Na+K+2Ca)> 0.5 apfu and C(Al+Fe3++2Ti) > 1.5 apfu
Nybøite is defined with
A position: Na dominant
C2+ position: Mg dominant
C3+ position: Al dominant
W position: (OH) dominant
The nybøite group minerals are sodium amphiboles defined with A(Na+K+2Ca)> 0.5 apfu and C(Al+Fe3++2Ti) > 1.5 apfu
Nybøite is defined with
A position: Na dominant
C2+ position: Mg dominant
C3+ position: Al dominant
W position: (OH) dominant
Element Weights:
Chemical Analysis
Oxide wt%:
| 1 | 2 | 3 | |
|---|---|---|---|
| SiO2 | 53.84 % | 50.89 % | 52.59 % |
| TiO2 | 0.16 % | 0.08 % | 0.22 % |
| Al2O3 | 12.92 % | 12.09 % | 9.60 % |
| MgO | 14.21 % | 12.42 % | 12.72 % |
| FeO | 5.03 % | 9.76 % | 5.18 % |
| MnO | 0.02 % | 0.07 % | 0.19 % |
| NiO | 0.11 % | ||
| CaO | 2.33 % | 2.93 % | 2.43 % |
| Na2O | 9.26 % | 8.42 % | 8.11 % |
| K2O | 0.14 % | 0.27 % | 0.00 % |
| Cl | 0.01 % | ||
| Fe2O3 | 7.60 % | ||
| H2O | 2.15 % | ||
| Total: | 98.03 % | 96.93 % | 100.79 % |
Empirical formulas:
| Sample ID | Empirical Formula |
|---|---|
| 1 | (Na0.72K0.02)(Na1.67Ca0.33)(Mg1.82Fe2+0.18)(Mg0.32Fe3+0.24Ti0.02Al1.43)(Mg0.8Fe2+0.2) (Si7.24Al0.76)022(OH)2 |
Sample references:
| ID | Type | Locality | Reference | Notes |
|---|---|---|---|---|
| 1 | Type Specimen | Nybø eclogite pod, Sørpollen, Vågsøy, Kinn, Vestland, Norway | ||
| 2 | Jianchang, Donghai Co., Lianyungang, Jiangsu, China | Sample from porphyroblastic eclogite. | ||
| 3 | Tianpu, Xin Co., Xinyang, Henan, China | Sample from the rim of amphibole grains in a jadeite-bearing granofels .The core of these grains are glaucophane. |
Crystallography of Nybøite
Crystal System:
Monoclinic
Class (H-M):
2/m - Prismatic
Space Group:
B2/m
Setting:
C2/m
Cell Parameters:
a = 9.665(1) Å, b = 17.752(2) Å, c = 5.303(1) Å
β = 104.11(1)°
β = 104.11(1)°
Ratio:
a:b:c = 0.544 : 1 : 0.299
Unit Cell V:
882.4 ų
Comment:
From Oberti et al. (2003)
Geological Environment
Paragenetic Mode(s):
| Paragenetic Mode | Earliest Age (Ga) |
|---|---|
| Stage 3b: Earth’s earliest hydrosphere | >4.45 |
| 17 : Marine authigenic Hadean minerals (see also #24) | |
| Stage 4b: Highly evolved igneous rocks | >3.0 |
| 35 : Ultra-alkali and agpaitic igneous rocks | |
| 36 : Carbonatites, kimberlites, and related igneous rocks |
Type Occurrence of Nybøite
General Appearance of Type Material:
A thin section with an amphibole taken from sympletic-free areas in a single 16 cm thick compositionally-layered sample
Place of Conservation of Type Material:
Mineralogical Gallery of the Museum National d’Histoire Naturelle, Paris (no. 181.55).
Empirical Formula of Type Material:
(Na0.72K0.02)(Na1.67Ca0.33)(Mg1.82Fe2+0.18)(Mg0.32Fe3+0.24Ti0.02Al1.43)(Mg0.8Fe2+0.2) (Si7.24Al0.76)022(OH)2
Geological Setting of Type Material:
The nybø eclogite pod
Associated Minerals at Type Locality:
Reference:
Synonyms of Nybøite
Other Language Names for Nybøite
Relationship of Nybøite to other Species
Member of:
Other Members of Nybøite Root Name Group:
| 'Ferri-fluoro-nybøite' | NaNa2(Mg3Fe3+2)(AlSi7O22)F2 | |
| 'Ferri-nybøite' | NaNa2(Mg3Fe3+2)(AlSi7O22)(OH)2 | Mon. |
| Ferro-ferri-nybøite | NaNa2(Fe2+3,Mg)Fe3+2)(AlSi7O22)(OH)2 | Mon. 2/m : B2/m |
| 'Ferro-nybøite' | NaNa2(Fe2+3Al2)(AlSi7O22)(OH)2 | Mon. |
| Fluoro-nybøite | NaNa2(Mg3Al2)(AlSi7O22)(F,OH)2 | Mon. 2/m : B2/m |
Common Associates
Associations Based on Photo Data: