Bertrandite
A valid IMA mineral species - grandfathered
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About Bertrandite
Emile Bertrand
Formula:
Be4(Si2O7)(OH)2
Colour:
Colourless, pale yellow
Lustre:
Vitreous
Hardness:
6 - 7
Specific Gravity:
2.59 - 2.6
Crystal System:
Orthorhombic
Name:
Named by Alexis Damour in honor of Émile Bertrand (1844 - 16 November 1909), French mineralogist and co-founder of the Société française de Minéralogie.
A common hydrothermal alteration product of beryl.
Visit gemdat.org for gemological information about Bertrandite.
Visit gemdat.org for gemological information about Bertrandite.Unique Identifiers
Mindat ID:
642
Long-form identifier:
mindat:1:1:642:6
IMA Classification of Bertrandite
Approved, 'Grandfathered' (first described prior to 1959)
IMA Formula:
Be4Si2O7(OH)2
First published:
1880
Classification of Bertrandite
9.BD.05
9 : SILICATES (Germanates)
B : Sorosilicates
D : Si2O7 groups, with additional anions; cations in tetrahedral [4] and greater coordination
9 : SILICATES (Germanates)
B : Sorosilicates
D : Si2O7 groups, with additional anions; cations in tetrahedral [4] and greater coordination
56.1.1.1
56 : SOROSILICATES Si2O7 Groups, With Additional O, OH, F and H2O
1 : Si2O7 Groups and O, OH, F, and H2O with cations in [4] coordination
56 : SOROSILICATES Si2O7 Groups, With Additional O, OH, F and H2O
1 : Si2O7 Groups and O, OH, F, and H2O with cations in [4] coordination
14.3.2
14 : Silicates not Containing Aluminum
3 : Silicates of Be
14 : Silicates not Containing Aluminum
3 : Silicates of Be
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 |
|---|---|---|
| Btd | 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 Bertrandite
Vitreous
Transparency:
Transparent
Comment:
Pearly on cleavage {001}
Colour:
Colourless, pale yellow
Streak:
White
Hardness:
6 - 7 on Mohs scale
Cleavage:
Perfect
Perfect on {001}
Distinct on {100}, {010} and {110}
Perfect on {001}
Distinct on {100}, {010} and {110}
Density:
2.59 - 2.6 g/cm3 (Measured) 2.61 g/cm3 (Calculated)
Optical Data of Bertrandite
Type:
Biaxial (-)
RI values:
nα = 1.591 nβ = 1.605 nγ = 1.614
2V:
Measured: 73° to 81°, Calculated: 76°
Max. Birefringence:
δ = 0.023
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
Dispersion:
r < v weak
Chemistry of Bertrandite
Mindat Formula:
Be4(Si2O7)(OH)2
Element Weights:
Elements listed:
Common Impurities:
Al,Fe,Ca
Crystallography of Bertrandite
Crystal System:
Orthorhombic
Class (H-M):
mm2 - Pyramidal
Space Group:
Cmc21
Cell Parameters:
a = 8.7135(4) Å, b = 15.268(1) Å, c = 4.5683(3) Å
Ratio:
a:b:c = 0.571 : 1 : 0.299
Unit Cell V:
607.76 ų (Calculated from Unit Cell)
Z:
4
Morphology:
Thin tabular, prismatic to needle-like.
Twinning:
Common on {011}, {021}; heart- or V-shaped twins.
Crystallographic forms of Bertrandite
Crystal Atlas:
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Bertrandite no.19 - Goldschmidt (1913-1926)
Bertrandite no.20 - Goldschmidt (1913-1926)
Bertrandite no.21 - Goldschmidt (1913-1926)
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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) |
|---|---|---|---|---|---|---|---|
| 0001126 | Bertrandite | Downs J W, Ross F K (1987) Neutron-diffraction study of bertrandite American Mineralogist 72 979-983 |  | 1987 | 0 | 293 | |
| 0007375 | Bertrandite | Hazen R M, Au A Y (1986) High-pressure crystal chemistry of phenakite (Be2SiO4) and bertrandite (Be4Si2O7(OH)2) Physics and Chemistry of Minerals 13 69-78 | 1986 | 0 | 293 | ||
| 0007376 | Bertrandite | Hazen R M, Au A Y (1986) High-pressure crystal chemistry of phenakite (Be2SiO4) and bertrandite (Be4Si2O7(OH)2) Physics and Chemistry of Minerals 13 69-78 | 1986 | 2.3 | 293 | ||
| 0007377 | Bertrandite | Hazen R M, Au A Y (1986) High-pressure crystal chemistry of phenakite (Be2SiO4) and bertrandite (Be4Si2O7(OH)2) Physics and Chemistry of Minerals 13 69-78 | 1986 | 4.1 | 293 |
CIF Raw Data - click here to close
X-Ray Powder Diffraction
Powder Diffraction Data:
| d-spacing | Intensity |
|---|---|
| 4.38 Å | (100) |
| 3.19 Å | (90) |
| 2.54 Å | (80) |
| 2.28 Å | (60) |
| 2.22 Å | (50) |
| 3.94 Å | (40) |
| 1.305 Å | (40) |
| 1.555 Å | (30) |
| 1.456 Å | (30) |
| 1.938 Å | (20) |
| 1.220 Å | (20b) |
| 0.813 Å | (20) |
Comments:
Mica Creek, Queensland, Australia. Data from Vernon and Williams (1960).
Geological Environment
Paragenetic Mode(s):
| Paragenetic Mode | Earliest Age (Ga) |
|---|---|
| Stage 4a: Earth’s earliest continental crust | >4.4-3.0 |
| 19 : Granitic intrusive rocks | |
| Stage 4b: Highly evolved igneous rocks | >3.0 |
| 34 : Complex granite pegmatites | |
| 35 : Ultra-alkali and agpaitic igneous rocks |
Geological Setting:
Granite fissures or miarolitic cavities, pegmatites, greisen. Alteration product of beryl, rarely primary mineral.
Type Occurrence of Bertrandite
Co-Type Localities:
Place of Conservation of Type Material:
National School of Mines, Paris, France.
Geological Setting of Type Material:
In pegmatite.
Associated Minerals at Type Locality:
Synonyms of Bertrandite
Other Language Names for Bertrandite
Dutch:Bertrandiet
German:Bertrandit
Hessenbergit
Hessenbergit
Russian:Бертрандит
Simplified Chinese:羟硅铍石
Spanish:Bertrandita
Traditional Chinese:羥矽鈹石
Varieties of Bertrandite
| Gel-Bertrandite | A glassy colloidal form of Bertrandite. Originally described from Lovozero massif, Kola Peninsula, Murmanskaja Oblast', Northern Region, Russia. |
Common Associates
Associated Minerals Based on Photo Data:
| 269 photos of Bertrandite associated with Quartz | SiO2 |
| 173 photos of Bertrandite associated with Albite | Na(AlSi3O8) |
| 101 photos of Bertrandite associated with Fluorapatite | Ca5(PO4)3F |
| 96 photos of Bertrandite associated with Muscovite | KAl2(AlSi3O10)(OH)2 |
| 84 photos of Bertrandite associated with Fluorite | CaF2 |
| 81 photos of Bertrandite associated with Smoky Quartz | SiO2 |
| 69 photos of Bertrandite associated with Rhodochrosite | MnCO3 |
| 57 photos of Bertrandite associated with Pyrite | FeS2 |
| 40 photos of Bertrandite associated with Beryl | Be3Al2(Si6O18) |
| 35 photos of Bertrandite associated with Adularia | KAlSi3O8 |
Related Minerals - Strunz-mindat Grouping
| 9.BD.10 | Hemimorphite | Zn4Si2O7(OH)2 · H2O |
| 9.BD.15 | Junitoite | CaZn2Si2O7 · H2O |
| 9.BD.20 | Tinzenite | Ca2Mn2+4Al4[B2Si8O30](OH)2 |
| 9.BD.20 | Axinite-(Fe) | Ca2Fe2+Al2BSi4O15OH |
| 9.BD.20 | Dubińskaite | Ca4Sc2Al4[Be2Si8O30](OH)2 |
| 9.BD.20 | Axinite-(Mg) | Ca2MgAl2BSi4O15OH |
| 9.BD.20 | Axinite-(Mn) | Ca2Mn2+Al2BSi4O15(OH) |
| 9.BD.25 | Vistepite | SnMn4B2Si4O16(OH)2 |
| 9.BD.30 | Boralsilite | Al16B6O30(Si2O7) |
| 9.BD.35 | Werdingite | (Mg,Fe)2Al14Si4B4O37 |
| 9.BD.40 | Vránaite | Al16B4Si4O38 |
Other Information
Electrical:
Pyroelectric.
Thermal Behaviour:
Before the blowpipe, infusible, but becomes opaque.
Notes:
Insoluble in nitric acid.
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 Bertrandite
mindat.org URL:
https://www.mindat.org/min-642.html
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Please feel free to link to this page.
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References for Bertrandite
Reference List:
Bertrand, Émile (1880) Nouveau minéral des environs de Nantes. Bulletin de Minéralogie, 3 (4). 96-100 doi:10.3406/bulmi.1880.1566
Damour, Augustin-Alexis (1883) Note et analyse sur le nouveau minéral des environs de Nantes. Bulletin de Minéralogie, 6 (8). 252-254 doi:10.3406/bulmi.1883.1824
Bertrand, Emile (1883) Nouveau minéral des environs de Nantes [bertrandite]. Bulletin de Minéralogie, 6 (8) 248-252 doi:10.3406/bulmi.1883.1823
Scharizer, R. (1888) Der Bertrandit von Pisek. Zeitschrift für Kristallographie, 14 (1). 33-42 doi:10.1524/zkri.1888.14.1.33
Bowman, H. L. (1911) On the occurrence of Bertrandite at the Cheesewring Quarry, near Liskeard, Cornwall. Mineralogical Magazine and Journal of the Mineralogical Society, 16 (73) 47-50 doi:10.1180/minmag.1911.016.073.06
Vogt, Thorolf (1912) II. Bertrandit von Iveland im südlichen Norwegen. Zeitschrift für Kristallographie - Crystalline Materials, 50 (1) 6 doi:10.1524/zkri.1912.50.1.6
Russell, Arther (1913) Notes on the occurrence of Bertrandite at some new localities in Cornwall. Mineralogical Magazine and Journal of the Mineralogical Society, 17 (78) 15-21 doi:10.1180/minmag.1913.017.78.04
Ito, T., West, J. (1932) The Structure of Bertrandite (H2Be4Si2O9) Zeitschrift für Kristallographie - Crystalline Materials, 83 (1) 384-393 doi:10.1524/zkri.1932.83.1.384
Pough, Frederick H. (1936) Bertrandite and epistilbite from Bedford, New York. American Mineralogist, 21 (4) 264-265
Phemister, James (1940) Note on an occurrence of bertrandite and beryl at the South Crofty mine, Cornwall (With Plate XXV.) Mineralogical Magazine and Journal of the Mineralogical Society, 25 (170) 573-578 doi:10.1180/minmag.1940.025.170.01
Vernon, R. H., Williams, K. L. (1960) Bertrandite from Mica Creek, Queensland. American Mineralogist, 45 (11-12) 1300-1303
Morgan, W. C. (1967) Genthelvite and bertrandite from the Cairngorm Mountains, Scotland. Mineralogical Magazine and Journal of the Mineralogical Society, 36 (277) 60-63 doi:10.1180/minmag.1967.036.277.08
Hazen, Robert M., Au, Andrew Y. (1986) High-pressure crystal chemistry of phenakite (Be2SiO4) and bertrandite (Be4Si2O7(OH)2) Physics and Chemistry of Minerals, 13 (2) 69-78 doi:10.1007/bf00311896
Hemingway, Bruce S., Barton, Mark D., Robie, R. A., Haselton, H. T. (1986) Heat capacities and thermodynamic functions for beryl, Be3Al2Si6O18, phenakite, Be2SiO4, euclase, BeAlSiO4(OH), bertrandite, Be4Si2O7(OH)2, and chrysoberyl, BeAl2O4. American Mineralogist, 71 (3-4) 557-568
Hofmeister, A. M., Hoering, T. C., Virgo, D. (1987) Vibrational spectroscopy of beryllium aluminosilicates: Heat capacity calculations from band assignments. Physics and Chemistry of Minerals, 14 (3) 205-224 doi:10.1007/bf00307985
Localities for Bertrandite
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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