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Ilímaussite-(Ce)

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Formula:
(Na,K)7-8(Ba,K)10Ce5(Nb,Ti)6(Si3O9)4(Si9O18)O6(O,OH)24
the formula associated with crystal structure refinement: (Ba,Na)10K3Na4.5Ce5(Nb,Ti)6[Si12O36][Si9O18(O,OH)24]O6
Colour:
Brownish yellow
Lustre:
Resinous
Hardness:
4
Specific Gravity:
3.6
Crystal System:
Trigonal
Name:
Named for the type locality at Nakalak (Nakalaq) Mountain, Ilimaussaq complex, Narsaq, Kitaa (West Greenland) Province, Greenland.
Unique combination of elements. One of a few minerals with dominant Ce and Nb, a feature shared, e.g., with nacareniosite-(Ce). A K,Ti-analogue is also known: Unnamed (K-Ti analogue of ilímaussite-(Ce)).

The structure is based on 3 pairs of (001) silicate sheets, that sandwich:
- CeO6 trigonal prisms + Na cations (A layer, with 2 equivalent silicate sheets comprising non-interconnected six-membered rings)
- NbO6 octahedra + Ba + K (O layer; the octahedra share corners with silicate tetrahedra)
- CeO6 trigonal prisms (A' layer, with 50% Si occupancy -> disored of basal oxygen atoms)
The layer sequence is AOA'O. Somewhat related to diversilite-(Ce).


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Classification of Ilímaussite-(Ce)Hide

Approved
Approval Year:
1965
9.CB.15

9 : SILICATES (Germanates)
C : Cyclosilicates
B : [Si3O9]6- 3-membered single rings, with insular complex anions
78.7.4.1

78 : Unclassified Silicates
7 :
17.8.14

17 : Silicates Containing other Anions
8 : Silicates with niobate or tantalate

Physical Properties of Ilímaussite-(Ce)Hide

Resinous
Colour:
Brownish yellow
Streak:
White
Hardness:
Comment:
ca. 4
Fracture:
Conchoidal
Density:
3.6 g/cm3 (Measured)    3.7 g/cm3 (Calculated)

Optical Data of Ilímaussite-(Ce)Hide

Type:
Uniaxial (+)
RI values:
nω = 1.689 nε = 1.695
Max Birefringence:
δ = 0.006
Image shows birefringence interference colour range (at 30µm thickness)
and does not take into account mineral colouration.
Surface Relief:
High

Chemical Properties of Ilímaussite-(Ce)Hide

Formula:
(Na,K)7-8(Ba,K)10Ce5(Nb,Ti)6(Si3O9)4(Si9O18)O6(O,OH)24

the formula associated with crystal structure refinement: (Ba,Na)10K3Na4.5Ce5(Nb,Ti)6[Si12O36][Si9O18(O,OH)24]O6
IMA Formula:
(Ba,Na)10K3Na4.5Ce5(Nb,Ti)6O6(Si12O36)(Si9O18)(O,OH)24

Crystallography of Ilímaussite-(Ce)Hide

Crystal System:
Trigonal
Class (H-M):
3 2 - Trapezohedral
Space Group:
R3 2
Cell Parameters:
a = 10.770(3) Å, c = 61.05(2) Å
Ratio:
a:c = 1 : 5.669
Unit Cell V:
6,132.64 ų (Calculated from Unit Cell)
Twinning:
polysynthetic
Comment:
Previously reported to be hexagonal

Type Occurrence of Ilímaussite-(Ce)Hide

General Appearance of Type Material:
lamellar aggregates, up to 1.5 cm
Geological Setting of Type Material:
hydrothermal ussingite-analcime vein cutting sodalite syenite
Associated Minerals at Type Locality:

Synonyms of Ilímaussite-(Ce)Hide

Other Language Names for Ilímaussite-(Ce)Hide

Common AssociatesHide

Associated Minerals Based on Photo Data:
Ussingite1 photo of Ilímaussite-(Ce) associated with Ussingite on mindat.org.

Related Minerals - Nickel-Strunz GroupingHide

9.CB.05RoeblingitePb2Ca6Mn2+(Si3O9)2(SO4)2(OH)2 · 4H2OMon. 2/m : B2/m
9.CB.10Diversilite-(Ce)Na2(Ba,K)6Fe2+Ce2Ti3(Si3O9)3(HSiO4)3(OH,H2O)9Trig. 3

Related Minerals - Hey's Chemical Index of Minerals GroupingHide

17.8.1EpistoliteNa2(Nb,Ti)2(Si2O7)O2 · nH2OTric.
17.8.2MurmaniteNa2Ti2(Si2O7)O2 · 2H2OTric.
17.8.3PerraultiteBaNaMn2+4Ti2(Si2O7)2O2(OH)2FMon. 2/m : B2/m
17.8.4Niocalite(Ca,Nb)4(Si2O7)(O,OH,F)2Mon.
17.8.5MongoliteCa4Nb6Si5O24(OH)10 · nH2OTet.
17.8.6FersmaniteCa4(Na,Ca)4(Ti,Nb)4(Si2O7)2O8F3Tric.
17.8.7Nacareniobsite-(Ce)NbNa3Ca3(Ce,REE )(Si2O7)2OF3Mon.
17.8.8Nenadkevichite(Na,◻)8Nb4(Si4O12)2(O,OH)4 · 8H2OOrth. mmm (2/m 2/m 2/m) : Pbam
17.8.9Natrokomarovite(Na,Ca,H)2Nb2Si2O10(OH,F)2 · H2OOrth.
17.8.10WöhleriteNaCa2(Zr,Nb)(Si2O7)(O,OH,F)2Mon. 2 : P21
17.8.11BelkoviteBa3(Nb,Ti)6(Si2O7)2O12Hex.
17.8.12BaotiteBa4(Ti,Nb)8Si4O28ClTet. 4/m : I41/a
17.8.13Shcherbakovite(K,Ba)KNa(Ti,Nb)2(Si4O12)O2Orth.
17.8.15Komarovite(Ca,Mn)Nb2[O3|Si2O7] · 3.5H2OOrth.
17.8.16Manganbelyankinite(Mn,Ca)(Ti,Nb)5O12 · 9H2O
17.8.17Niobophyllite(K,Na)3(Fe,Mn)6(Nb,Ti)2Si8(O,OH,F)31Tric.
17.8.18Caesium-Kupletskite(Cs,K,Na)3(Mn,Fe2+)7(Ti,Nb)2Si8O24(O,OH,F)7

Other InformationHide

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

References for Ilímaussite-(Ce)Hide

Reference List:
Sort by Year (asc) | by Year (desc) | by Author (A-Z) | by Author (Z-A)
Meddelelser om Grønland: 181(7): 3-7.
American Mineralogist (1969) 54, 992.
Giovanni Ferraris, Angela Gula, Natalia V. Zubkova, Dmitry Yu. Pushcharovsky, Elena R. Gobetchiya, Igor V. Pekov, and Knut Eldjarn (2004): The crystal structure of Ilimaussite-(Ce) and the “Ilimaussite” problem, Canadian Mineralogist, Vol. 42, 787-795
Anthony, J.W., Bideaux, R.A., Bladh, K.W. and Nichols, M.C., Eds. Handbook of Mineralogy, Mineralogical Society of America, Chantilly, VA 20151-1110, USA. http://www.handbookofmineralogy.org/ (2016)

Internet Links for Ilímaussite-(Ce)Hide

Localities for Ilímaussite-(Ce)Hide

This 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.

Locality ListHide

- This locality has map coordinates listed. - This locality has estimated coordinates. ⓘ - Click for 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). Struck out - Mineral was erroneously reported from this locality. Faded * - Never found at this locality but inferred to have existed at some point in the past (eg from pseudomorphs.)

All localities listed without proper references should be considered as questionable.
Greenland
 
  • Kujalleq
    • Narsaq
Petersen, O.V. (2001): List of all minerals identified in the Ilímaussaq alkaline complex, South Greenland. Geology of Greenland Survey Bulletin. 190, 25-33
        • Taseq area
          • Nakalak Mt (Nakalaq; Nakkaalaaq)
Semenov, E.I., Kazakova, M.E., Bukin, V.J. (1968): Ilimaussite, a new rare earth – niobium – barium silicate, from Ilimaussaq, South Greenland, Medd. Groenland, Vol. 181 (7), 3-7
Russia
 
  • Northern Region
    • Murmanskaya Oblast'
[World of Stones 95:5-6, p64] (but probably actually Diversilite-(Ce) and not really Nb-dominant Ilimaussite-(Ce).)
Mineral and/or Locality  
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