Brenkite
A valid IMA mineral species
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About Brenkite
the interesting part is on the left upper zone in the rubble
Schellkopf, Brenk, Brohltal, Ahrweiler, Rhineland-Palatinate, Germany
Schellkopf, Brenk, Brohltal, Ahrweiler, Rhineland-Palatinate, Germany
Formula:
Ca2(CO3)F2
Colour:
Colorless
Hardness:
5
Specific Gravity:
3.10
Crystal System:
Orthorhombic
Name:
Named for the type locality at Brenk, Germany.
This page provides mineralogical data about Brenkite.
Unique Identifiers
Mindat ID:
764
Long-form identifier:
mindat:1:1:764:7
Similar Names
| Brunckit | A synonym of Sphalerite |
| Brunckite | A synonym of 'Schalenblende' |
| Brünnikite | A synonym of Apophyllite Group |
IMA Classification of Brenkite
Approved
Approval year:
1977
Classification of Brenkite
5.BC.05
5 : CARBONATES (NITRATES)
B : Carbonates with additional anions, without H2O
C : With alkali-earth cations
5 : CARBONATES (NITRATES)
B : Carbonates with additional anions, without H2O
C : With alkali-earth cations
16a.3.6.1
16a : ANHYDROUS CARBONATES CONTAINING HYDROXYL OR HALOGEN
3 : (AB)2(XO3)Zq
16a : ANHYDROUS CARBONATES CONTAINING HYDROXYL OR HALOGEN
3 : (AB)2(XO3)Zq
12.1.6
12 : Carbonates with other anions
1 : Carbonates with halides
12 : Carbonates with other anions
1 : Carbonates with halides
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 |
|---|---|---|
| Bki | 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 Brenkite
Transparency:
Translucent
Colour:
Colorless
Streak:
White
Hardness:
5 on Mohs scale
Cleavage:
None Observed
Density:
3.10(4) g/cm3 (Measured) 3.126 g/cm3 (Calculated)
Optical Data of Brenkite
Type:
Biaxial (-)
RI values:
nα = 1.525 nβ = 1.59 nγ = 1.593
2V:
Measured: 26° to 28°, Calculated: 22°
Max. Birefringence:
δ = 0.068
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 (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.
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:
r > v
Optical Extinction:
X = a; Y = a.
Chemistry of Brenkite
Mindat Formula:
Ca2(CO3)F2
Element Weights:
Elements listed:
Crystallography of Brenkite
Crystal System:
Orthorhombic
Class (H-M):
mmm(2/m2/m2/m) - Dipyramidal
Space Group:
Pbcn
Setting:
Pbcn
Cell Parameters:
a = 7.650(4) Å, b = 7.550(2) Å, c = 6.548(2) Å
Ratio:
a:b:c = 1.013 : 1 : 0.867
Unit Cell V:
378.20 ų (Calculated from Unit Cell)
Z:
4
Morphology:
Lath-like crystals showing forms {010}, {110}, {102}, and {021}.
Crystal Structure
Load
Unit Cell | Unit Cell Packed
2x2x2 | 3x3x3 | 4x4x4
Unit Cell | Unit Cell Packed
2x2x2 | 3x3x3 | 4x4x4
Show
Big Balls | Small Balls | Just Balls | Spacefill
Polyhedra Off | Si Polyhedra | All Polyhedra
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Big Balls | Small Balls | Just Balls | Spacefill
Polyhedra Off | Si Polyhedra | All Polyhedra
Remove metal-metal sticks
Display Options
Black Background | White Background
Perspective On | Perspective Off
2D | Stereo | Red-Blue | Red-Cyan
Black Background | White Background
Perspective On | Perspective Off
2D | Stereo | Red-Blue | Red-Cyan
View
CIF File Best | x | y | z | a | b | c
CIF File Best | x | y | z | a | b | c
Rotation
Stop | Start
Stop | Start
Labels
Console Off | On | Grey | Yellow
Console Off | On | Grey | Yellow
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) |
|---|---|---|---|---|---|---|---|
| 0015679 | Brenkite | Leufer U, Tillmanns E (1980) Die kristallstruktur von brenkit, Ca2F2CO3 Tschermaks Mineralogische und Petrographische Mitteilungen 27 261-266 | 1980 | 0 | 293 |
CIF Raw Data - click here to close
X-Ray Powder Diffraction
Powder Diffraction Data:
| d-spacing | Intensity |
|---|---|
| 2.794 Å | (100) |
| 3.028 Å | (80) |
| 3.006 Å | (80) |
| 1.835 Å | (80) |
| 2.486 Å | (70) |
| 3.276 Å | (60) |
| 2.265 Å | (60) |
Geological Environment
Paragenetic Mode(s):
| Paragenetic Mode | Earliest Age (Ga) |
|---|---|
| Near-surface Processes | |
| 23 : Subaerial aqueous alteration by non-redox-sensitive fluids (see also #47) | |
| 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 Brenkite
General Appearance of Type Material:
Prismatic crystals
Place of Conservation of Type Material:
Johannes Gutenberg University, Mainz, Germany; National Museum of Natural History, Washington, D.C., USA, 137256.
Geological Setting of Type Material:
In voids and fissures in a porphryritic selbergite
Associated Minerals at Type Locality:
Synonyms of Brenkite
Other Language Names for Brenkite
Common Associates
Associations Based on Photo Data:
| 8 photos of Brenkite associated with Phillipsite Subgroup | (Ca0.5,K,Na,Ba0.5)4-7[Al4-7Si12-9O32] . 12H2O |
| 6 photos of Brenkite associated with Zeophyllite | Ca13Si10O28(OH)2F8 · 6H2O |
| 4 photos of Brenkite associated with Aegirine | NaFe3+Si2O6 |
| 3 photos of Brenkite associated with Polylithionite | KLi2Al(Si4O10)(F,OH)2 |
| 1 photo of Brenkite associated with Nepheline | Na3K(Al4Si4O16) |
| 1 photo of Brenkite associated with Phillipsite-K | K6(Si10Al6)O32 · 12H2O |
Related Minerals - Strunz-mindat Grouping
| 5.BC.10 | Rouvilleite | Na3CaMn2+(CO3)3F |
| 5.BC.15 | Podlesnoite | BaCa2(CO3)2F2 |
Other Information
Notes:
Dissolves with effervescence in dilute HCl.
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 Brenkite
mindat.org URL:
https://www.mindat.org/min-764.html
Please feel free to link to this page.
Please feel free to link to this page.
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External Links:
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References for Brenkite
Reference List:
Fleischer, Michael, Chao, George Y., Pabst, and Adolf (1979) New Mineral Names. American Mineralogist, 64 (1-2) 241-245
Localities for Brenkite
Showing 4 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.
Germany (TL) | |
| Neues Jahrb.Min. (1978) +1 other reference |
Poland | |
| Volume 26 +1 other reference |
Sweden | |
| Lindh (2012) |
USA | |
| Rocks & Min.: 60:229. |
Quick NavTopAbout BrenkiteUnique IdentifiersSimilar NamesIMA Classification Classification Mineral SymbolsPhysical Properties Optical Data Chemistry Crystallography Crystal StructureX-Ray Powder DiffractionGeological EnvironmentType Occurrence SynonymsOther LanguagesCommon AssociatesStrunz-MindatOther InformationInternet Links References Localities Locality List
Schellkopf, Brenk, Brohltal, Ahrweiler, Rhineland-Palatinate, Germany