Mineralogy Database

Combeite Mineral Data

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General Combeite Information

Help on Chemical  Formula: Chemical Formula: Na2Ca2Si3O9
Help on Composition: Composition: Molecular Weight = 354.39 gm
   Sodium   12.97 %  Na   17.49 % Na2O
   Calcium  22.62 %  Ca   31.65 % CaO
   Silicon  23.78 %  Si   50.86 % SiO2
   Oxygen   40.63 %  O
           ______        ______ 
           100.00 %      100.00 % = TOTAL OXIDE
Help on Empirical Formula: Empirical Formula: Na2Ca2Si3O9
Help on Environment: Environment: In nephelinite (Mt. Shaheru, Congo); in nephelinite and ash ejecta (Oldoinyo Lengai volcano, Tanzania).
Help on IMA Status: IMA Status: Valid Species (Pre-IMA) 1957
Help on Locality: Locality: On Mt. Shaheru, the extinct southern cone of Mt. Nyiragongo, Kivu Province, Congo (Zaire). Link to MinDat.org Location Data.
Help on Name Origin: Name Origin: Named for Arthur Delmar Combe, Geological Survey of Uganda.
 

Combeite Image

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  Combeite

Comments: Crystalline cleavage fragment of combeite.
Location: Mont Saint Hilaire, Quebec, Canada. Scale: See Photo.
© Jeff Weissman / Photographic Guide to Mineral Species

Combeite Crystallography

Help on Axial Ratios: Axial Ratios: a:c = 1:1.25839
Help on Cell Dimensions: Cell Dimensions: a = 10.48, c = 13.188, Z = 6; V = 1,254.39 Den(Calc)= 2.81
Help on Crystal System: Crystal System: Trigonal - Trapezohedral H-M Symbol (3 2) Space Group: P 3221,P 3121
Help on X Ray Diffraction: X Ray Diffraction: By Intensity(I/Io): 2.657(1), 2.607(0.8), 3.304(0.7),
 

Physical Properties of Combeite

Help on Cleavage: Cleavage: None
Help on Color: Color: Colorless.
Help on Density: Density: 2.844
Help on Diaphaneity: Diaphaneity: Transparent
Help on Streak: Streak: white
 

Optical Properties of Combeite

Help on Gladstone-Dale: 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
Help on Optical Data: Optical Data: Uniaxial (+), w=1.598, e=1.598, bire=0.0000.
 

Calculated Properties of Combeite

Help on Electron Density: Electron Density: Bulk Density (Electron Density)=2.82 gm/cc
note: Specific Gravity of Combeite =2.84 gm/cc.
Help on Fermion Index: Fermion Index: Fermion Index = 0.01
Boson Index = 0.99
Help on Photoelectric: Photoelectric: PECombeite = 3.90 barns/electron
U=PECombeite x rElectron Density= 11.01 barns/cc.
Help on Radioactivity: Radioactivity: GRapi = 0 (Gamma Ray American Petroleum Institute Units)
Combeite is Not Radioactive
 

Combeite Classification

Help on  Dana Class: Dana Class: 61.01.02a.05 (61)Cyclosilicate Six-Membered Rings
  (61.01)with [Si6O18] rings; possible (OH) and Al substitution
  (61.01.02a)Lovozerite group (HEX and HEX-R subgroup)
 
61.01.02a.01 Lovozerite H4Na2Ca(Zr,Ti)[Si6O18] R 3m 3 2/m
 
61.01.02a.02 Kazakovite Na6MnTiSi6O18 R 3m 3 2/m
 
61.01.02a.03 Tisinalite Na3H3(Mn,Ca,Fe)TiSi6(O,OH)18•2(H2O) R 3m 3 2/m
 
61.01.02a.04 Zirsinalite Na6(Ca,Mn,Fe)Zr[Si6O18] R 3m 3 2/m
 
61.01.02a.05 Combeite Na2Ca2Si3O9 P 3221,P 3121 3 2
 
61.01.02a.06 Kapustinite! Na5.5Mn0.25ZrSi6O16(OH)2 C 2/m 2/m
Help on  Strunz Class: Strunz Class: 09.CJ.15 09 - SILICATES (Germanates)
  09.C - Cyclosilicates
  09.CJ -[Si6O18]12- 6-membered single rings (sechser-Einfachringe),
 
09.CJ.15 Combeite Na2Ca2Si3O9 P 3221,P 3121 3 2
 
09.CJ.15 Kazakovite Na6MnTiSi6O18 R 3m 3 2/m
 
09.CJ.15 Lovozerite H4Na2Ca(Zr,Ti)[Si6O18] R 3m 3 2/m
 
09.CJ.15 Zirsinalite Na6(Ca,Mn,Fe)Zr[Si6O18] R 3m 3 2/m
 
09.CJ.15 Kapustinite! Na5.5Mn0.25ZrSi6O16(OH)2 C 2/m 2/m
 
09.CJ.15 Tisinalite Na3H3(Mn,Ca,Fe)TiSi6(O,OH)18•2(H2O) R 3m 3 2/m
 
09.CJ.15 Litvinskite! Na2([],Na,Mn)Zr[Si6O12(OH,O)6] Cm m
 

Other Combeite Information

Help on References: References: NAME( AntBidBlaNic2) PHYS. PROP.(Enc. of Minerals,2nd ed.,1990) OPTIC PROP.(Enc. of Minerals,2nd ed.,1990)
Help on See Also: 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

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Print or Cut-and-Paste your Combeite Specimen Label here :

Combeite

Na2Ca2Si3O9
Dana No: 61.01.02a.05 Strunz No: 09.CJ.15
Locality:

 

Notes:

 

 
   
 


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