Barringtonite
Valid as an unnamed mineral
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About Barringtonite
Formula:
MgCO3 · 2H2O
Crystal System:
Triclinic
Name:
Named for Barrington Tops, type locality.
Originally reported from Rainbow Falls, Semphill Creek, Barrington Tops, Gloucester Co., New South Wales, Australia.
Unique Identifiers
Mindat ID:
538
Long-form identifier:
mindat:1:1:538:4
Similar Names
| Farringtonite | A valid IMA mineral species | Mg3(PO4)2 |
| Harringtonite | A synonym of Mesolite | |
| Warringtonite | A synonym of Brochantite |
IMA Classification of Barringtonite
IMA status notes:
Unnamed (probably valid)
Approval history:
Unnamed, but probably valid.
Classification of Barringtonite
5.CA.15
5 : CARBONATES (NITRATES)
C : Carbonates without additional anions, with H2O
A : With medium-sized cations
5 : CARBONATES (NITRATES)
C : Carbonates without additional anions, with H2O
A : With medium-sized cations
15.1.5.1
15 : HYDRATED NORMAL CARBONATES
1 : A(XO3)·xH2O
15 : HYDRATED NORMAL CARBONATES
1 : A(XO3)·xH2O
11.3.2
11 : Carbonates
3 : Carbonates of Mg
11 : Carbonates
3 : Carbonates of Mg
Optical Data of Barringtonite
Type:
Biaxial (+)
RI values:
nα = 1.458 nβ = 1.473 nγ = 1.501
2V:
Measured: 73° , Calculated: 74°
Max. Birefringence:
δ = 0.043
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:
Moderate (negative)
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:
none
Chemistry of Barringtonite
Mindat Formula:
MgCO3 · 2H2O
Element Weights:
Elements listed:
Crystallography of Barringtonite
Crystal System:
Triclinic
Cell Parameters:
a = 9.15 Å, b = 6.2 Å, c = 6.09 Å
α = 94°, β = 95.5°, γ = 108.7°
α = 94°, β = 95.5°, γ = 108.7°
Ratio:
a:b:c = 1.476 : 1 : 0.982
Unit Cell V:
323.89 ų (Calculated from Unit Cell)
Other Language Names for Barringtonite
Common Associates
Associations Based on Photo Data:
| 3 photos of Barringtonite associated with Lansfordite | MgCO3 · 5H2O |
Related Minerals - Strunz-mindat Grouping
| 5.CA.05 | Nesquehonite | MgCO3 · 3H2O |
| 5.CA.10 | Lansfordite | MgCO3 · 5H2O |
| 5.CA.20 | Hellyerite | NiCO3 · 5.5H2O |
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 Barringtonite
mindat.org URL:
https://www.mindat.org/min-538.html
Please feel free to link to this page.
Please feel free to link to this page.
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References for Barringtonite
Localities for Barringtonite
Showing 2 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 | |
| Mineralogical Magazine 1965 34 : 370-372 |
Greece | |
| Kolitsch et al. (2014) |
Maricopa County, Arizona, USA