Trembathite
A valid IMA mineral species
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About Trembathite
Formula:
Mg3B7O13Cl
Often Fe-bearing; atomic proportion of Fe compared to Mg from approximately 0.32 to 0.5.
Colour:
Colourless to pale blue, dark brown
Lustre:
Vitreous
Hardness:
6 - 8
Specific Gravity:
2.84 - 3.34
Crystal System:
Trigonal
Member of:
Name:
Name after Lowell T. Trembath (1936-1994), Professor of Mineralogy, University of New Brunswick, Fredericton, Canada, for his dedication to mineralogical research and teaching.
Type Locality:
Dimorph of:
Boracite Group. The magnesium analogue of congolite, always (at standard temperature and pressure) containing some iron, from Mg0.68Fe0.32 to Mg0.5Fe0.5.
Compare with boracite.
Compare with boracite.
Unique Identifiers
Mindat ID:
4010
Long-form identifier:
mindat:1:1:4010:1
IMA Classification of Trembathite
Approved
Approval year:
1991
First published:
1992
Classification of Trembathite
6.GA.10
6 : BORATES
G : Heptaborates and other megaborates
A : Tekto-heptaborates
6 : BORATES
G : Heptaborates and other megaborates
A : Tekto-heptaborates
25.6.2.2
25 : ANHYDROUS BORATES CONTAINING HYDROXYL OR HALOGEN
6 : Hexaborates
25 : ANHYDROUS BORATES CONTAINING HYDROXYL OR HALOGEN
6 : Hexaborates
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 |
|---|---|---|
| Tba | 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 Trembathite
Vitreous
Transparency:
Transparent
Colour:
Colourless to pale blue, dark brown
Comment:
Dark brown crystals known from the Boulby mine
Streak:
White
Hardness:
6 - 8 on Mohs scale
Fracture:
Conchoidal
Density:
2.84 - 3.34 g/cm3 (Measured) 3.225 g/cm3 (Calculated)
Optical Data of Trembathite
Type:
Uniaxial (-)
RI values:
nω = 1.684(2) nε = 1.668(2)
Max. Birefringence:
δ = 0.016
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.
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.
Surface Relief:
Moderate
Chemistry of Trembathite
Mindat Formula:
Mg3B7O13Cl
Often Fe-bearing; atomic proportion of Fe compared to Mg from approximately 0.32 to 0.5.
Often Fe-bearing; atomic proportion of Fe compared to Mg from approximately 0.32 to 0.5.
Element Weights:
Elements listed:
Common Impurities:
Mn,Ca
Crystallography of Trembathite
Crystal System:
Trigonal
Class (H-M):
3m - Ditrigonal Pyramidal
Space Group:
R3c
Cell Parameters:
a = 8.588(2) Å, c = 21.050(6) Å
Ratio:
a:c = 1 : 2.451
Unit Cell V:
1,344.52 ų (Calculated from Unit Cell)
Z:
6
Morphology:
Pseudocubic rhombohedra.
Twinning:
Microscopic polysynthetic twinning typical.
Crystal Structure
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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) |
|---|---|---|---|---|---|---|---|
| 0005564 | Trembathite | Schindler M, Hawthorne F C (1998) The crystal structure of trembathite, (Mg1.55Fe1.43Mn0.02)B7O13Cl, a mineral of the boracite group: An example of the insertion of a cluster into a three-dimensional net The Canadian Mineralogist 36 1195-1201 |  | 1998 | 0 | 293 |
CIF Raw Data - click here to close
X-Ray Powder Diffraction
Powder Diffraction Data:
| d-spacing | Intensity |
|---|---|
| 3.028 Å | (100) |
| 2.050 Å | (73) |
| 2.711 Å | (66) |
| 2.144 Å | (37) |
| 3.497 Å | (34) |
| 1.828 Å | (25) |
| 2.475 Å | (23) |
Geological Environment
Paragenetic Mode(s):
| Paragenetic Mode | Earliest Age (Ga) |
|---|---|
| Near-surface Processes | |
| 25 : Evaporites (prebiotic) |
Type Occurrence of Trembathite
General Appearance of Type Material:
Pseudocubic rhombohedra, to 2 cm.
Place of Conservation of Type Material:
Royal Ontario Museum, Toronto, Ontario, Canada, M44741.
Geological Setting of Type Material:
Evaporite deposit.
Associated Minerals at Type Locality:
Synonyms of Trembathite
Other Language Names for Trembathite
Relationship of Trembathite to other Species
Member of:
Other Members of Boracite Group:
| Boracite | Mg3(B7O13)Cl | Orth. mm2 : Pca21 |
| Chambersite | Mn2+3(B7O13)Cl | Orth. mm2 : Pca21 |
| Congolite | Fe2+3B7O13Cl | Trig. 3m : R3c |
| Ericaite | Fe2+3(B7O13)Cl | Orth. mm2 : Pca21 |
Common Associates
Associations Based on Photo Data:
Related Minerals - Strunz-mindat Grouping
| 6.GA.05 | Ericaite | Fe2+3(B7O13)Cl |
| 6.GA.05 | Chambersite | Mn2+3(B7O13)Cl |
| 6.GA.05 | Boracite | Mg3(B7O13)Cl |
| 6.GA.10 | Congolite | Fe2+3B7O13Cl |
| 6.GA.30 | Korzhinskite | Ca(B2O4) · H2O |
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 Trembathite
mindat.org URL:
https://www.mindat.org/min-4010.html
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Please feel free to link to this page.
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References for Trembathite
Reference List:
Roulston, B. V., Waugh, D. C. E. (1981) A borate mineral assemblage from Penobsquis and Salt Springs evaporite deposits of southern New Brunswick. The Canadian Mineralogist, 19 (2) 291-301
Localities for Trembathite
Showing 5 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.
Canada | |
| Grice et al. (1996) |
| Burns et al. (1992) +1 other reference |
| Grice et al. (2005) |
Poland | |
| PIECZKA et al. (2012) +1 other reference |
UK | |
| Schindler et al. (1998) +1 other reference |
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Boulby Mine, Loftus, Redcar and Cleveland, North Yorkshire, England, UK