Fluorchegemite
A valid IMA mineral species
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Formula:
Ca7(SiO4)3F2
Colour:
Colorless
Hardness:
5½ - 6
Specific Gravity:
2.91 (Calculated)
Crystal System:
Orthorhombic
Member of:
Name:
For the mineral chegemite and its fluorine content.
Unique Identifiers
Mindat ID:
42739
Long-form identifier:
mindat:1:1:42739:1
GUID
(UUID V4):
(UUID V4):
c3002da8-f83a-491e-b263-411b76c1cd69
IMA Classification of Fluorchegemite
Approved
IMA Formula:
Ca7(SiO4)3F2
Approval year:
2012
First published:
2015
Type description reference:
Galuskina, Irina O., Krüger, Biljana, Galuskin, Evgeny V., Armbruster, Thomas, Gazeev, Viktor M., Włodyka, Roman, Dulski, Mateusz, Dzierżanowski, Piotr (2015) Fluorchegemite, Ca7(SiO4)3F2, a new mineral from the edgrewite-bearing endoskarn zone of an altered xenolith in ignimbrites from upper Chegem caldera, Northern Caucasus, Kabardino-Balkaria, Russia: occurrence, crystal structure, and new data on the mineral assemblages. The Canadian Mineralogist, 53 (2) 325-344 doi:10.3749/canmin.1400084
Classification of Fluorchegemite
9.AF.50
9 : SILICATES (Germanates)
A : Nesosilicates
F : Nesosilicates with additional anions; cations in [4], [5] and/or only [6] coordination
9 : SILICATES (Germanates)
A : Nesosilicates
F : Nesosilicates with additional anions; cations in [4], [5] and/or only [6] coordination
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 |
|---|---|---|
| Fcgm | 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 Fluorchegemite
Colour:
Colorless
Streak:
White
Hardness:
5½ - 6 on Mohs scale
Hardness:
VHN50=480 - 511 kg/mm2 - Vickers
Cleavage:
Imperfect/Fair
Imperfect on (010).
Imperfect on (010).
Fracture:
Irregular/Uneven
Density:
2.91 g/cm3 (Calculated)
Comment:
Density could not be measured due to numerous inclusions.
Optical Data of Fluorchegemite
Type:
Biaxial (-)
RI values:
nα = 1.610(2) nβ = 1.615(2) nγ = 1.619(2)
2V:
Measured: 80° (8), Calculated: 84°
Max Birefringence:
δ = 0.009
Image shows birefringence interference colour range (at 30µm thickness)
and does not take into account mineral colouration.
and does not take into account mineral colouration.
Surface Relief:
Moderate
Dispersion:
r > v, weak
Optical Extinction:
X = a; Y = b.
Pleochroism:
Non-pleochroic
Chemistry of Fluorchegemite
Mindat Formula:
Ca7(SiO4)3F2
Elements listed:
Crystallography of Fluorchegemite
Crystal System:
Orthorhombic
Class (H-M):
mmm (2/m 2/m 2/m) - Dipyramidal
Cell Parameters:
a = 5.0620(1) Å, b = 11.3917(2) Å, c = 23.5180(3) Å
Ratio:
a:b:c = 0.444 : 1 : 2.064
Unit Cell V:
1356.16 ų
Z:
4
Morphology:
Irregular grains up to 0.2 mm.
Twinning:
Twins have been noted.
Comment:
space group Pbnm
X-Ray Powder Diffraction
Powder Diffraction Data:
| d-spacing | Intensity |
|---|---|
| 3.636 Å | (52) |
| 3.013 Å | (57) |
| 2.991 Å | (56) |
| 2.832 Å | (51) |
| 2.718 Å | (63) |
| 2.699 Å | (46) |
| 2.531 Å | (100) |
| 1.905 Å | (95) |
Comments:
Calculated data based on material from Xenolith no. 1, Lakargi Mountain, Upper Chegem volcanic caldera, Russia. Data from the type description.
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) |
Type Occurrence of Fluorchegemite
General Appearance of Type Material:
Irregular grains up to 0.2 mm.
Place of Conservation of Type Material:
Fersman Mineralogical Museum of the Russian Academy of Sciences, Moscow, Russia, catalogue number 4163/1.
Geological Setting of Type Material:
An edgrewite-bearing zone of endoskarn at the contact of a large altered calciferous xenolith within ignimbrites of the Upper Chegem Caldera, Russia.
Associated Minerals at Type Locality:
Reference:
Galuskina, I.O., Krüger, B., Galuskin, E.V. ,Armbruster, T., Gazeev, V.M., Włodyka, R., Dulski, M. & Dzierżanowski, P. (2015) Fluorchegemite, Ca7(SiO4)3F2, a new mineral from the edgrewitebearing endoskarn zone of an altered xenolith in ignimbrites from Upper Chegem Caldera, Northern Caucasus, Kabardina-balkaria, Russia; Occurrence, crystal structure, and new data on the mineral assemblages. The Canadian Mineralogist, 53, 325-344.
Synonyms of Fluorchegemite
Relationship of Fluorchegemite to other Species
Member of:
Other Members of this group:
| Chegemite | Ca7(SiO4)3(OH)2 | Orth. mmm (2/m 2/m 2/m) |
| Edgrewite | Ca9(SiO4)4F2 | Mon. 2/m : P21/b |
| Hydroxyledgrewite | Ca9(SiO4)4(OH)2 | Mon. 2/m : P21/b |
| Kumtyubeite | Ca5(SiO4)2F2 | Mon. 2/m : P21/b |
| Reinhardbraunsite | Ca5(SiO4)2(OH,F)2 | Mon. 2/m : P21/b |
Forms a series with:
Related Minerals - Strunz-mindat Grouping
| 9.AF. | Chegemite | Ca7(SiO4)3(OH)2 |
| 9.AF. | Barwoodite | Mn2+6Nb5+(SiO4)2O3(OH)3 |
| 9.AF. | Jingwenite-(Y) | YAlV4+(SiO4)O2(OH)2 |
| 9.AF.05 | Sillimanite | Al2(SiO4)O |
| 9.AF.05 | Xenolite | Al10Si8O31 |
| 9.AF.10 | Andalusite | Al2(SiO4)O |
| 9.AF.10 | Kanonaite | Mn3+Al(SiO4)O |
| 9.AF.15 | Kyanite | Al2(SiO4)O |
| 9.AF.20 | Mullite | Al4+2xSi2-2xO10-x |
| 9.AF.20 | Krieselite | Al2(GeO4)F2 |
| 9.AF.23 | Boromullite | Al9BSi2O19 |
| 9.AF.25 | Yoderite | Mg(Al,Fe3+)3(SiO4)2O(OH) |
| 9.AF.30 | Magnesiostaurolite | Mg(Mg,Li)3(Al,Mg)18Si8O44(OH)4 |
| 9.AF.30 | Staurolite | Fe2+2Al9Si4O23(OH) |
| 9.AF.30 | Zincostaurolite | Zn2Al9Si4O23(OH) |
| 9.AF.35 | Topaz | Al2(SiO4)(F,OH)2 |
| 9.AF.40 | Norbergite | Mg3(SiO4)F2 |
| 9.AF.45 | Alleghanyite | Mn2+5(SiO4)2(OH)2 |
| 9.AF.45 | Chondrodite | Mg5(SiO4)2F2 |
| 9.AF.45 | Reinhardbraunsite | Ca5(SiO4)2(OH,F)2 |
| 9.AF.45 | Kumtyubeite | Ca5(SiO4)2F2 |
| 9.AF.45 | Hydroxylchondrodite | Mg5(SiO4)2(OH)2 |
| 9.AF.50 | Humite | Mg7(SiO4)3F2 |
| 9.AF.50 | Manganhumite | (Mn2+,Mg)7(SiO4)3(OH)2 |
| 9.AF.50 | Unnamed (Ca-analogue of Humite) | Ca7(SiO4)4F2 |
| 9.AF.50 | Unnamed (OH-analogue of humite) | Mg7(SiO4)3(OH)2 |
| 9.AF.55 | Clinohumite | Mg9(SiO4)4F2 |
| 9.AF.55 | Sonolite | Mn2+9(SiO4)4(OH)2 |
| 9.AF.55 | Hydroxylclinohumite | Mg9(SiO4)4(OH)2 |
| 9.AF.60 | Leucophoenicite | Mn2+7(SiO4)3(OH)2 |
| 9.AF.65 | Ribbeite | Mn2+5(SiO4)2(OH)2 |
| 9.AF.70 | Jerrygibbsite | Mn2+9(SiO4)4(OH)2 |
| 9.AF.75 | Franciscanite | Mn2+6(V5+,◻)2(SiO4)2(O,OH)6 |
| 9.AF.75 | Örebroite | Mn2+3(Sb5+,Fe3+)(SiO4)(O,OH)3 |
| 9.AF.75 | Welinite | Mn2+6(W6+,Mg)2(SiO4)2(O,OH)6 |
| 9.AF.75 | Scorticoite | Mn6(Sb,◻)Σ2(SiO4)2O3(OH)3 |
| 9.AF.80 | Ellenbergerite | Mg6(Mg,Ti,Zr,◻)2(Al,Mg)6Si8O28(OH)10 |
| 9.AF.85 | Chloritoid | (Fe2+,Mg,Mn2+)Al2(SiO4)O(OH)2 |
| 9.AF.85 | Magnesiochloritoid | MgAl2(SiO4)O(OH)2 |
| 9.AF.85 | Ottrélite | (Mn2+,Fe2+,Mg)Al2(SiO4)O(OH)2 |
| 9.AF.90 | Poldervaartite | CaCa[SiO3(OH)](OH) |
| 9.AF.90 | Olmiite | CaMn2+[SiO3(OH)](OH) |
| 9.AF.95 | Pilawite-(Y) | Ca2Y2Al4(SiO4)4O2(OH)2 |
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 Fluorchegemite
mindat.org URL:
https://www.mindat.org/min-42739.html
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References for Fluorchegemite
Reference List:
Williams, P. A., Hatert, F., Pasero, M., Mills, S. J. (2012) New minerals and nomenclature modifications approved in 2012. CNMNC Newsletter No 13. Mineralogical Magazine, 76 (3) 807-817 doi:10.1180/minmag.2012.076.3.26
Galuskina, Irina O., Krüger, Biljana, Galuskin, Evgeny V., Armbruster, Thomas, Gazeev, Viktor M., Włodyka, Roman, Dulski, Mateusz, Dzierżanowski, Piotr (2015) Fluorchegemite, Ca7(SiO4)3F2, a new mineral from the edgrewite-bearing endoskarn zone of an altered xenolith in ignimbrites from upper Chegem caldera, Northern Caucasus, Kabardino-Balkaria, Russia: occurrence, crystal structure, and new data on the mineral assemblages. The Canadian Mineralogist, 53 (2) 325-344 doi:10.3749/canmin.1400084
Localities for Fluorchegemite
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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