General Combeite Information Chemical Formula: |
Na2Ca2Si3O9 |
Composition: |
Molecular Weight = 354.39 gm |
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Sodium 12.97 % Na 17.49 % Na2O |
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Calcium 22.62 % Ca 31.65 % CaO |
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Silicon 23.78 % Si 50.86 % SiO2 |
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Oxygen 40.63 % O |
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______ ______ |
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100.00 % 100.00 % = TOTAL OXIDE |
Empirical Formula: |
Na2Ca2Si3O9 |
Environment: |
In nephelinite (Mt. Shaheru, Congo); in nephelinite and ash ejecta (Oldoinyo Lengai volcano, Tanzania). |
IMA Status: |
Valid Species (Pre-IMA) 1957 |
Locality: |
On Mt. Shaheru, the extinct southern cone of Mt. Nyiragongo, Kivu Province, Congo (Zaire). Link to MinDat.org Location Data. |
Name Origin: |
Named for Arthur Delmar Combe, Geological Survey of Uganda. |
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Images:
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Combeite Crystallography Axial Ratios: |
a:c = 1:1.25839 |
Cell Dimensions: |
a = 10.48, c = 13.188, Z = 6; V = 1,254.39 Den(Calc)= 2.81 |
Crystal System: |
Trigonal - TrapezohedralH-M Symbol (3 2) Space Group: P 3221,P 3121 |
X Ray Diffraction: |
By Intensity(I/Io): 2.657(1), 2.607(0.8), 3.304(0.7), |
Crystal Structure:
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Mouse
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| Physical Properties of Combeite Cleavage: |
None |
Color: |
Colorless. |
Density: |
2.844 |
Diaphaneity: |
Transparent |
Streak: |
white |
| Optical Properties of Combeite Gladstone-Dale: |
CI meas= -0.023 (Excellent) - where the CI = (1-KPDmeas/KC) |
CI calc= -0.036 (Excellent) - where the CI = (1-KPDcalc/KC) KPDcalc= 0.2128,KPDmeas= 0.2103,KC= 0.2055 Ncalc = 1.58 Optical Data: |
Uniaxial (+), w=1.598, e=1.598, bire=0.0000. |
| Calculated Properties of Combeite Electron Density: |
Bulk Density (Electron Density)=2.82 gm/cc |
note: Specific Gravity of Combeite =2.84 gm/cc. Fermion Index: |
Fermion Index = 0.01 |
Boson Index = 0.99 Photoelectric: |
PECombeite = 3.90 barns/electron |
U=PECombeite x rElectron Density= 11.01 barns/cc. Radioactivity: |
GRapi = 0 (Gamma Ray American Petroleum Institute Units) |
Combeite is Not Radioactive | Combeite Classification Dana Class: |
61.01.02a.05 (61)Cyclosilicate Six-Membered Rings |
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(61.01)with [Si6O18] rings; possible (OH) and Al substitution |
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(61.01.02a)Lovozerite group (HEX and HEX-R subgroup) |
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Strunz Class: |
09.CJ.15 09 - SILICATES (Germanates) |
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09.C - Cyclosilicates |
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09.CJ -[Si6O18]12- 6-membered single rings (sechser-Einfachringe), |
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| Other Combeite Information References: |
NAME( AntBidBlaNic2) PHYS. PROP.(Enc. of Minerals,2nd ed.,1990) OPTIC PROP.(Enc. of Minerals,2nd ed.,1990) |
See Also: |
Links to other databases for Combeite : |
1 - Am. Min. Crystal Structure Database 2 - Athena 3 - EUROmin Project 4 - Ecole des Mines de Paris 5 - GeoScienceWorld 6 - Google Images 7 - Google Scholar 8 - Handbook of Mineralogy (MinSocAm) 9 - Handbook of Mineralogy (UofA) 10 - MinDAT 11 - Mineralienatlas (Deutsch) 12 - Online Mineral Museum 13 - QUT Mineral Atlas 14 - Ruff.Info 15 - WWW-MINCRYST Search for Combeite using: Visit our Advertisers for Combeite : A Bijoux Google Search for CombeiteAdam's Minerals Google Search for Combeite Cape Minerals Google Search for Combeite Dakota Matrix Minerals Google Search for Combeite Excalibur Mineral Corp. Google Search for Combeite Exceptional Minerals Google Search for Combeite John Betts Fine Minerals Search for Combeite McDougall Minerals Google Search for Combeite Mineral News Website Link Rock and Mineral Shows Google Search for Combeite Weinrich Minerals, Inc. Google Search for Combeite Ask about Combeite here : Print or Cut-and-Paste your Combeite Specimen Label here :
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