Bredigite
A valid IMA mineral species - grandfathered
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About Bredigite
Formula:
Ca7Mg(SiO4)4
Colour:
Colorless, grey
Lustre:
Vitreous
Specific Gravity:
3.42
Crystal System:
Orthorhombic
Name:
Named in honor of Dr. Max Albrecht Bredig (20 June 1902 - 21 November 1977), physical chemist, who studied the polymorphism of Ca2SiO4. Dr. Bredig was former Associate Director of the Chemistry Division Oak Ridge National Laboratory, and expert in the chemistry of molten salts and chemistry of the solid state, especially high temperature and crystal chemistry.
Type Locality:
Anthropogenic "Ca7MgSi4O16" is described by Žáček et al. (2005).
Unique Identifiers
Mindat ID:
762
Long-form identifier:
mindat:1:1:762:9
IMA Classification of Bredigite
Approved, 'Grandfathered' (first described prior to 1959)
First published:
1948
Type description reference:
Classification of Bredigite
9.AD.20
9 : SILICATES (Germanates)
A : Nesosilicates
D : Nesosilicates without additional anions; cations in [6] and/or greater coordination
9 : SILICATES (Germanates)
A : Nesosilicates
D : Nesosilicates without additional anions; cations in [6] and/or greater coordination
51.4.1.1
51 : NESOSILICATES Insular SiO4 Groups Only
4 : Insular SiO4 Groups Only with cations in [6] and >[6] coordination
51 : NESOSILICATES Insular SiO4 Groups Only
4 : Insular SiO4 Groups Only with cations in [6] and >[6] coordination
14.5.7
14 : Silicates not Containing Aluminum
5 : Silicates of Ca
14 : Silicates not Containing Aluminum
5 : Silicates of Ca
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 |
|---|---|---|
| Bdi | 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 Bredigite
Vitreous
Transparency:
Transparent
Colour:
Colorless, grey
Streak:
White
Cleavage:
Distinct/Good
Distinct on {130}
Distinct on {130}
Density:
3.42 g/cm3 (Measured) 3.32 g/cm3 (Calculated)
Optical Data of Bredigite
Type:
Biaxial (+)
RI values:
nα = 1.712 nβ = 1.716 nγ = 1.725
2V:
Measured: 30° , Calculated: 68°
Max. Birefringence:
δ = 0.013
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
Dispersion:
relatively strong
Pleochroism:
Visible
Comments:
In thick sections, X = pale violet; Y = Z = colorless to pale green. X=b, Y=a, Z=c.
Chemistry of Bredigite
Mindat Formula:
Ca7Mg(SiO4)4
Element Weights:
Elements listed:
Common Impurities:
Ti,Fe,Mn,Ba,F
Crystallography of Bredigite
Crystal System:
Orthorhombic
Class (H-M):
mm2 - Pyramidal
Space Group:
Pnn2
Cell Parameters:
a = 10.909(9) Å, b = 18.34(1) Å, c = 6.739(9) Å
Ratio:
a:b:c = 0.595 : 1 : 0.367
Unit Cell V:
1,348.28 ų (Calculated from Unit Cell)
Z:
4
Twinning:
Simple contact and cyclical on {110}.
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) |
|---|---|---|---|---|---|---|---|
| 0000494 | Bredigite | Moore P B, Araki T (1976) The crystal structure of bredigite and the genealogy of some alkaline earth orthosilicates American Mineralogist 61 74-87 |  | 1976 | 0 | 293 |
CIF Raw Data - click here to close
X-Ray Powder Diffraction
Powder Diffraction Data:
| d-spacing | Intensity |
|---|---|
| 2.730 Å | (100) |
| 2.663 Å | (100) |
| 2.259 Å | (80) |
| 1.923 Å | (80) |
| 2.067 Å | (60) |
| 1.574 Å | (60) |
| 1.554 Å | (60) |
Geological Environment
Paragenetic Mode(s):
| Paragenetic Mode | Earliest Age (Ga) |
|---|---|
| Stage 3a: Earth’s earliest Hadean crust | >4.50 |
| 9 : Lava/xenolith minerals (hornfels, sanidinite facies) | |
| High-? alteration and/or metamorphism | |
| 31 : Thermally altered carbonate, phosphate, and iron formations | |
| Stage 5: Initiation of plate tectonics | <3.5-2.5 |
| 40 : Regional metamorphism (greenschist, amphibolite, granulite facies) | |
| Stage 10a: Neoproterozoic oxygenation/terrestrial biosphere | <0.6 |
| 50 : Coal and/or oil shale minerals | <0.36 |
| 51 : Pyrometamorphic minerals (see also #54 and #56) | <0.36 |
| Stage 10b: Anthropogenic minerals | <10 Ka |
| 54 : Coal and other mine fire minerals (see also #51 and #56) | |
| 56 : Slag and smelter minerals (see also #51 and #55) |
Type Occurrence of Bredigite
General Appearance of Type Material:
Crystals are squat, barrel- or boat-shaped, with pseudohexagonal cross sections, or as slender prismatic crystals, to 2mm
Place of Conservation of Type Material:
The Natural History Museum, London, England, 1956, 385.
Geological Setting of Type Material:
Type specimen was from slag (Middlesbrough type specimen of Tilley and Vincent)
Associated Minerals at Type Locality:
Reference:
Other Language Names for Bredigite
Common Associates
Related Minerals - Strunz-mindat Grouping
| 9.AD. | Adrianite | Ca12(Al4Mg3Si7)O32Cl6 |
| 9.AD.05 | Larnite | Ca2SiO4 |
| 9.AD.10 | Calcio-olivine | Ca2SiO4 |
| 9.AD.15 | Merwinite | Ca3Mg(SiO4)2 |
| 9.AD.25 | Midbarite | Ca3Mg2(V5+2Si)O12 |
| 9.AD.25 | Menzerite-(Y) | (Y2Ca)Mg2(SiO4)3 |
| 9.AD.25 | Uvarovite | Ca3Cr3+2(SiO4)3 |
| 9.AD.25 | Eltyubyuite | Ca12Fe3+10Si4O32Cl6 |
| 9.AD.25 | Eringaite | Ca3Sc2(SiO4)3 |
| 9.AD.25 | Henritermierite | Ca3Mn3+2(SiO4)2[◻(OH)4] |
| 9.AD.25 va | 'Hydrougrandite' | (Ca,Mg,Fe2+)3(Fe3+,Al)2[(OH)4(SiO4)2] |
| 9.AD.25 | Calderite | Mn2+3Fe3+2(SiO4)3 |
| 9.AD.25 | Nikmelnikovite | Ca12(Fe2+Fe3+3Al3◻)[SiO4]6[◻(OH)4]5◻4 |
| 9.AD.25 | Hutcheonite | Ca3Ti2(SiO4)(AlO4)2 |
| 9.AD.25 | Wadalite | (Ca,Mg)6(Al,Fe3+)4((Si,Al)O4)3O4Cl3 |
| 9.AD.25 | Rubinite | Ca3Ti3+2(SiO4)3 |
| 9.AD.25 | Kerimasite | Ca3Zr2(SiO4)(Fe3+O4)2 |
| 9.AD.25 | Holtstamite | Ca3Al2(SiO4)2[◻(OH)4] |
| 9.AD.25 | Spessartine | Mn2+3Al2(SiO4)3 |
| 9.AD.25 | Toturite | Ca3Sn2(SiO4)(Fe3+O4)2 |
| 9.AD.25 | Kimzeyite | Ca3Zr2(SiO4)(AlO4)2 |
| 9.AD.25 | 'Khoharite' | Mg3Fe3+2(SiO4)3 |
| 9.AD.25 | Irinarassite | Ca3Sn2(SiO4)(AlO4)2 |
| 9.AD.25 | Knorringite | Mg3Cr3+2(SiO4)3 |
| 9.AD.25 | Goldmanite | Ca3V3+2(SiO4)3 |
| 9.AD.25 | 'Blythite' | Mn2+3Mn3+2[SiO4]3 |
| 9.AD.25 | 'Skiagite' | Fe2+3Fe3+2[SiO4]3 |
| 9.AD.25 | 'UM1984-37-SiO:CrMn' | Mn2+3Cr3+2(SiO4)3 |
| 9.AD.25 | Almandine | Fe2+3Al2(SiO4)3 |
| 9.AD.25 va | 'Yamatoite' | (Mn2+,Ca)3(V3+,Al)2(SiO4)3 |
| 9.AD.25 | Momoiite | Mn2+3V3+2(SiO4)3 |
| 9.AD.25 | Grossular | Ca3Al2(SiO4)3 |
| 9.AD.25 | Andradite | Ca3Fe3+2(SiO4)3 |
| 9.AD.25 | Morimotoite | Ca3(TiFe2+)(SiO4)3 |
| 9.AD.25 | Majorite | Mg3(MgSi)(SiO4)3 |
| 9.AD.25 | Pyrope | Mg3Al2(SiO4)3 |
| 9.AD.25 | Schorlomite | Ca3Ti2(SiO4)(Fe3+O4)2 |
| 9.AD.30 | Hafnon | Hf(SiO4) |
| 9.AD.30 | Zircon | Zr(SiO4) |
| 9.AD.30 | Coffinite | U(SiO4) · nH2O |
| 9.AD.30 | Thorite | Th(SiO4) |
| 9.AD.30 va | 'Auerlite' | near Th(Si,P)O4 |
| 9.AD.30 | Stetindite-(Ce) | Ce4+SiO4 |
| 9.AD.35 | 'Tombarthite-(Y)' | Y4(Si,H4)4O12-x(OH)4+2x |
| 9.AD.35 | Huttonite | ThSiO4 |
| 9.AD.40 | Eulytine | Bi4(SiO4)3 |
| 9.AD.45 | Reidite | Zr(SiO4) |
| 9.AD.55 | Jeffbenite | Mg3Al2Si3O12 |
Other Information
Notes:
Dissolves readily in the weakest acids, leaving a silica pseudomorph, gives no effervescence, and yields abundant evidence of calcium.
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 Bredigite
mindat.org URL:
https://www.mindat.org/min-762.html
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Please feel free to link to this page.
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References for Bredigite
Reference List:
Tilley, C. E., Vincent, H. C. G. (1948) The occurrence of an orthorhombic high-temperature form of Ca2SiO4 (bredigite) in the Scawt Hill contact-zone and as a constituent of slags. Mineralogical Magazine and Journal of the Mineralogical Society, 28 (200). 255-271 doi:10.1180/minmag.1948.028.200.02
Tilley, C. E., Vincent, H. C. G. (1948) The occurrence of an orthorhombic high-temperature form of Ca2SiO4 (bredigite) in the Scawt Hill contact-zone and as a constituent of slags. Mineralogical Magazine and Journal of the Mineralogical Society, 28 (200). 255-271 doi:10.1180/minmag.1948.028.200.02
Bridge, Thomas E. (1966) Bredigite, larnite, and γ dicalcium silicates from Marble Canyon. American Mineralogist, 51 (11-12) 1766-1774
Moore, Paul Brian (1973) Bracelets and pinwheels: A topological-geometrical approach to the calcium orthosilicate and alkali sulfate structures. American Mineralogist, 58 (1-2) 32-42
Moore, Paul Brian, Araki, Takaharu (1976) The crystal structure of bredigite and the genealogy of some alkaline earth orthosilicates. American Mineralogist, 61 (1-2) 74-87
Žáček, Vladimír, Skála, Roman, Chlupáčová, Marta, Dvořák, (2005) Ca-Fe3+-rich, Si-undersaturated buchite from Zelenky, North-Bohemian Brown Coal Basin, Czech Republic. European Journal of Mineralogy, 17 (4). 623-634 doi:10.1127/0935-1221/2005/0017-0623
Localities for Bredigite
Showing 22 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.
Czech Republic | |
| Žáček et al. (2011) |
Georgia | |
| Galuskina et al. (2015) +1 other reference |
Germany | |
| Skrzyńska et al. (2023) |
| Blass et al. (1998) |
| Sharygin (2012) | |
| in the collection of Christof Schäfer | |
| in the collection of Christof Schäfer | |
| Blaß et al. (2014) |
Israel | |
| Kahlenberg et al. (2019) |
| Sharygin et al. (2008) |
Jordan | |
| Sokol +9 other references |
Middle East | |
| Gross (1977) | |
Russia | |
| Armbruster et al. (2011) +1 other reference |
| Sokol et al. (2019) +2 other references |
UK | |
| Mineralogical Society of America - ... |
| Sabine et al. (1985) |
| Tilley et al. (1948) +2 other references |
| Tindle (2008) | |
| American Mineralogist: 33: 786 |
| Excalibur Mineral Corp. - Mineral News +1 other reference |
USA | |
| Smith (1991) |
| Bridge (1966) +1 other reference |
Quick NavTopAbout BredigiteUnique IdentifiersIMA Classification Classification Mineral SymbolsPhysical Properties Optical Data Chemistry Crystallography Crystal StructureX-Ray Powder DiffractionGeological EnvironmentType Occurrence Other LanguagesCommon AssociatesStrunz-MindatOther InformationInternet Links References Localities Locality List
Xenolith CS-036, Caspar quarry, Ettringen, Vordereifel, Mayen-Koblenz, Rhineland-Palatinate, Germany