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Combeite

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Big Photo

Mt Oldoinyo Lengai (Ol Doinyo Lengai), Arusha Region, Tanzania
© Tony Peterson

Show Combeite Photos (3)



Formula:
Na
 
2
Ca
 
2
(Si
 
6
O
 
18
)
 
0.5
System:Trigonal
Member of:Lovozerite Group


Lovozerite Group.

Classification of Combeite

IMA status:Valid - first described prior to 1959 (pre-IMA) - "Grandfathered"
Strunz 8th edition ID:8/E.15-10
Nickel-Strunz 10th (pending) edition ID:9.CJ.15a

9 : SILICATES (Germanates)
C : Cyclosilicates
J : [Si6O18]12- 6-membered single rings (sechser-Einfachringe), without insular complex anions
Dana 8th edition ID:61.1.2a.5

61 : CYCLOSILICATES Six-Membered Rings
1 : Six-Membered Rings with [Si6O18] rings; possible (OH) and Al substitution
Hey's CIM Ref.:14.6.1

14 : Silicates not Containing Aluminum
6 : Silicates of Ca with alkali or Mg or both
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Type Occurrence of Combeite

Type Locality:Mt Shaheru, Mt Nyiragongo, Goma, Kivu, Democratic Republic of Congo (Zaïre)
Year of Discovery:1957

Crystallography of Combeite

Crystal System:Trigonal
Cell Parameters:a = 10.42Å, c = 13.14Å
Ratio:a:c = 1 : 1.261
Unit Cell Volume:V 1,235.55 ų (Calculated from Unit Cell)

Optical Data of Combeite

Type:Uniaxial (+)
RI values: nω = 1.598 nε = 1.598
Maximum Birefringence:δ = 0.000

Chart shows birefringence interference colour range (at 30µm thickness) and does not take into account mineral colouration.
Surface Relief:Moderate

Chemical Properties of Combeite

Formula:
Na
 
2
Ca
 
2
(Si
 
6
O
 
18
)
 
0.5
Idealised Formula:
Na
 
2
Ca
 
2
Si
 
3
O
 
9
Essential elements:Ca, Na, O, Si
All elements listed in formula:Ca, Na, O, Si
Common Impurities:Ti,Zr,Al,Fe,Mn,Mg,Ba,K,F,Cl,S,P

Relationship of Combeite to other Species

Member of:Lovozerite Group
Other Members of Group:

- +
Imandrite
Na
 
12
Ca
 
3
Fe
3+
2
(Si
 
6
O
 
18
)
 
2
Kapustinite
Na
 
5
(Na,Mn
2+
 
)
 
<1
Zr(H
 
2
Si
 
6
O
 
18
)
Kazakovite
Na
 
6
Mn
2+
 
Ti(Si
 
6
O
 
18
)
Koashvite
Na
 
6
(Ca,Mn)(Ti,Fe)Si
 
6
O
 
18
 · H
 
2
O
Litvinskite
Na
 
2
(◻,Na,Mn)ZrSi
 
6
O
 
12
(OH,O)
 
6
Lovozerite
Na
 
2
CaZr(H
 
4
Si
 
6
O
 
18
) · H
 
2
O
Tisinalite
Na
 
3
H
 
3
(Mn,Ca,Fe)TiSi
 
6
(O,OH)
 
18
 · 2H
 
2
O
Zirsinalite
Na
 
6
(Ca,Mn
2+
 
,Fe
2+
 
)Zr(Si
 
6
O
 
18
)
Related Minerals - Nickel-Strunz Grouping):

- +
9.CJ.05Bazzite
Be
 
3
Sc
 
2
(Si
 
6
O
 
18
)
9.CJ.05Beryl
Be
 
3
Al
 
2
(Si
 
6
O
 
18
)
9.CJ.05Indialite
Mg
 
2
Al
 
3
(AlSi
 
5
O
 
18
)
9.CJ.05Stoppaniite
Be
 
3
Fe
3+
2
(Si
 
6
O
 
18
) · H
 
2
O
9.CJ.10Cordierite
(Mg,Fe)
 
2
Al
 
3
(AlSi
 
5
O
 
18
)
9.CJ.10Sekaninaite
(Fe,Mg)
 
2
Al
 
3
(AlSi
 
5
O
 
18
)
9.CJ.15bImandrite
Na
 
12
Ca
 
3
Fe
3+
2
(Si
 
6
O
 
18
)
 
2
9.CJ.15aKazakovite
Na
 
6
Mn
2+
 
Ti(Si
 
6
O
 
18
)
9.CJ.15cKoashvite
Na
 
6
(Ca,Mn)(Ti,Fe)Si
 
6
O
 
18
 · H
 
2
O
9.CJ.15aLovozerite
Na
 
2
CaZr(H
 
4
Si
 
6
O
 
18
) · H
 
2
O
9.CJ.15aTisinalite
Na
 
3
H
 
3
(Mn,Ca,Fe)TiSi
 
6
(O,OH)
 
18
 · 2H
 
2
O
9.CJ.15aZirsinalite
Na
 
6
(Ca,Mn
2+
 
,Fe
2+
 
)Zr(Si
 
6
O
 
18
)
9.CJ.15aLitvinskite
Na
 
2
(◻,Na,Mn)ZrSi
 
6
O
 
12
(OH,O)
 
6
9.CJ.15aKapustinite
Na
 
5
(Na,Mn
2+
 
)
 
<1
Zr(H
 
2
Si
 
6
O
 
18
)
9.CJ.25Baratovite
KCa
 
7
(Ti,Zr)
 
2
Li
 
3
Si
 
12
O
 
36
F
 
2
9.CJ.25Katayamalite
KCa
 
7
Ti
 
2
Li
 
3
Si
 
12
O
 
36
(OH)
 
2
9.CJ.25Aleksandrovite
KCa
 
7
Sn
 
2
Li
 
3
Si
 
12
O
 
36
F
 
2
9.CJ.30Dioptase
CuSiO
 
3
 · H
 
2
O
9.CJ.35Kostylevite
K
 
2
Zr(Si
 
3
O
 
9
) · H
 
2
O
9.CJ.40Petarasite
Na
 
5
Zr
 
2
(Si
 
6
O
 
18
)(Cl,OH) · 2H
 
2
O
9.CJ.45Gerenite-(Y)
(Ca,Na)
 
2
(Y,REE)
 
3
Si
 
6
O
 
18
 · 2H
 
2
O
9.CJ.50Odintsovite
K
 
2
Na
 
4
Ca
 
3
Ti
 
2
Be
 
4
Si
 
12
O
 
38
9.CJ.55Mathewrogersite
Pb
 
7
FeAl
 
3
GeSi
 
12
O
 
36
(OH,H
 
2
O)
 
6
9.CJ.60Pezzottaite
Cs(Be
 
2
Li)Al
 
2
(Si
 
6
O
 
18
)
Related Minerals - Hey's Index Grouping:

- +
14.6.2Pectolite
NaCa
 
2
(HSi
 
3
O
 
9
)
14.6.3Pectolite-M2abc
NaCa
 
2
[HSi
 
3
O
 
9
]
14.6.4Denisovite
Ca
 
2
(K,Na)Si
 
3
O
 
8
(F,OH)
 
2
14.6.5Tokkoite
K
 
2
Ca
 
4
Si
 
7
O
 
17
(O,OH,F)
 
4
14.6.6Mountainite
KNa
 
2
Ca
 
2
[Si
 
8
O
 
19
(OH)] · 6H
 
2
O
14.6.7Rhodesite
KHCa
 
2
Si
 
8
O
 
19
 · 5H
 
2
O
14.6.8Miserite
K(Ca,Ce)
 
4
Si
 
5
O
 
13
(OH)
 
3
14.6.9Åkermanite
Ca
 
2
Mg(Si
 
2
O
 
7
)
14.6.10Monticellite
CaMgSiO
 
4
14.6.11Merwinite
Ca
 
3
Mg(SiO
 
4
)
 
2
14.6.12Diopside
CaMgSi
 
2
O
 
6
14.6.13Tremolite
☐{Ca
 
2
}{Mg
 
5
}(Si
 
8
O
 
22
)(OH)
 
2

Other Names for Combeite

Synonyms:
H-Combeite
Other Languages:
German:Combeit
Russian:Комбит
Spanish:Combeita

Other Information

Health Warning:No information on health risks for this material has been entered into the database. You should always treat mineral specimens with care.

References for Combeite

Reference List:

- +
Sahama, T.G. and K. Hytönen (1957): Götzenite and combeite, two new
silicates from the Belgian Congo. Mineral. Mag., 31, 503-510. [abs. in American Mineralogist 43, 791.

American Mineralogist: 67: 418.

Ohsato, H., Takeuchi, Y., Maki, I. (1986): Structure of Na4Ca4[Si6O18]. Acta Crystallographica C42, 934-937.

Fischer, R.X., Tillmanns, E. (1987): Revised data for combeite, Na2Ca2Si3O9. Acta Crystallographica C43, 1852-1854.

Fischer, R.X., Tillmanns, E. (1983): Die Kristallstrukturen von natürlichem Na2Ca2Si3O9 vom Mt. Shaheru (Zaire) und aus dem Mayener Feld (Eifel), N. Jb. Mineral. Mh., 1983, 49-59.

Internet Links for Combeite

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  • Raman and XRD data at RRUFF project
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    • Localities for Combeite

    The map shows a selection of localities that have latitude and longitude coordinates recorded. Click on the symbol to view information about a locality. The symbol next to localities in the list can be used to jump to that position on the map.
    Hide Locality List
    (TL) indicates type locality. ? indicates mineral may be doubtful at this locality. All other localities listed without reference should be considered as uncertain and unproven until references can be found.
    Democratic Republic of Congo (Zaïre)
     
    • Kivu
      • Goma
        • Mt Nyiragongo
    		Mineralogical Magazine 31 (1957) 698-699; Fischer, R.X. Tillmanns, E. (1983): Die Kristallstrukturen von natürlichem Na2Ca2Si3O9 vom Mt. Shaheru (Zaire) und aus dem Mayener Feld (Eifel), N. Jb. Mineral. Mh. 49-59.
    Germany
     
    • Rhineland-Palatinate
      • Eifel
        • Mayen
          • Ettringen
            • Bellerberg volcano
              • Southern lava flow
                • Mayener Feld
    		Fischer, R.X. Tillmanns, E. (1983): Die Kristallstrukturen von natürlichem Na2Ca2Si3O9 vom Mt. Shaheru (Zaire) und aus dem Mayener Feld (Eifel), N. Jb. Mineral. Mh. 49-59.
    Tanzania
     
    • Arusha Region
    		www.koeln.netsurf.de/~w.steffens/other.htm
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