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About Ilímaussite-(Ce)Hide

the formula associated with crystal structure refinement: (Ba,Na)10K3Na4.5Ce5(Nb,Ti)6[Si12O36][Si9O18(O,OH)24]O6
Brownish yellow
Specific Gravity:
Crystal System:
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).

Classification of Ilímaussite-(Ce)Hide

Approval Year:

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

78 : Unclassified Silicates
7 :

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

Physical Properties of Ilímaussite-(Ce)Hide

Brownish yellow
ca. 4
3.6 g/cm3 (Measured)    3.7 g/cm3 (Calculated)

Optical Data of Ilímaussite-(Ce)Hide

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:

Chemical Properties of Ilímaussite-(Ce)Hide


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

Crystallography of Ilímaussite-(Ce)Hide

Crystal System:
Class (H-M):
3 2 - Trapezohedral
Space Group:
R3 2
Cell Parameters:
a = 10.770(3) Å, c = 61.05(2) Å
a:c = 1 : 5.669
Unit Cell V:
6,132.64 ų (Calculated from Unit Cell)
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:
1 photo of Ilímaussite-(Ce) associated with UssingiteNa2AlSi3O8OH

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
17.8.5MongoliteCa4Nb6Si5O24(OH)10 · nH2OTet.
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
17.8.12BaotiteBa4Ti8Si4O28ClTet. 4/m : I41/a
17.8.15Komarovite(Ca,Mn)(Nb,Ti)2[Si2O7](O,F)3 · 3.5H2OOrth.
17.8.16Manganbelyankinite(Mn,Ca)(Ti,Nb)5O12 · 9H2O

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. (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.
  • 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
        • 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
Knut Eldjarn collection
  • Murmansk Oblast
[World of Stones 95:5-6, p64] (but probably actually Diversilite-(Ce) and not really Nb-dominant Ilimaussite-(Ce).)
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